30个类手写Spring核心原理之自定义ORM（下）（7）

3 基于Spring JDBC实现关键功能

3.1 ClassMappings

ClassMappings主要定义基础的映射类型，代码如下：

package com.tom.orm.framework;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.math.BigDecimal;
import java.sql.Date;
import java.sql.Timestamp;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

public class ClassMappings {

private ClassMappings(){}

static final Set<Class<?>> SUPPORTED_SQL_OBJECTS = new HashSet<Class<?>>();

static {
//只要这里写了，默认支持自动类型转换
Class<?>[] classes = {
boolean.class, Boolean.class,
short.class, Short.class,
int.class, Integer.class,
long.class, Long.class,
float.class, Float.class,
double.class, Double.class,
String.class,
Date.class,
Timestamp.class,
BigDecimal.class
};
SUPPORTED_SQL_OBJECTS.addAll(Arrays.asList(classes));
}

static boolean isSupportedSQLObject(Class<?> clazz) {
return clazz.isEnum() || SUPPORTED_SQL_OBJECTS.contains(clazz);
}

public static Map<String, Method> findPublicGetters(Class<?> clazz) {
Map<String, Method> map = new HashMap<String, Method>();
Method[] methods = clazz.getMethods();
for (Method method : methods) {
if (Modifier.isStatic(method.getModifiers()))
continue;
if (method.getParameterTypes().length != 0)
continue;
if (method.getName().equals("getClass"))
continue;
Class<?> returnType = method.getReturnType();
if (void.class.equals(returnType))
continue;
if(!isSupportedSQLObject(returnType)){
continue;
}
if ((returnType.equals(boolean.class)
|| returnType.equals(Boolean.class))
&& method.getName().startsWith("is")
&& method.getName().length() > 2) {
map.put(getGetterName(method), method);
continue;
}
if ( ! method.getName().startsWith("get"))
continue;
if (method.getName().length() < 4)
continue;
map.put(getGetterName(method), method);
}
return map;
}

public static Field[] findFields(Class<?> clazz){
return clazz.getDeclaredFields();
}

public static Map<String, Method> findPublicSetters(Class<?> clazz) {
Map<String, Method> map = new HashMap<String, Method>();
Method[] methods = clazz.getMethods();
for (Method method : methods) {
if (Modifier.isStatic(method.getModifiers()))
continue;
if ( ! void.class.equals(method.getReturnType()))
continue;
if (method.getParameterTypes().length != 1)
continue;
if ( ! method.getName().startsWith("set"))
continue;
if (method.getName().length() < 4)
continue;
if(!isSupportedSQLObject(method.getParameterTypes()[0])){
continue;
}
map.put(getSetterName(method), method);
}
return map;
}

public static String getGetterName(Method getter) {
String name = getter.getName();
if (name.startsWith("is"))
name = name.substring(2);
else
name = name.substring(3);
return Character.toLowerCase(name.charAt(0)) + name.substring(1);
}

private static String getSetterName(Method setter) {
String name = setter.getName().substring(3);
return Character.toLowerCase(name.charAt(0)) + name.substring(1);
}
}

3.2 EntityOperation

EntityOperation主要实现数据库表结构和对象类结构的映射关系，代码如下：

package com.tom.orm.framework;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.Transient;
import org.apache.log4j.Logger;
import org.springframework.jdbc.core.RowMapper;
import javax.core.common.utils.StringUtils;

/**
* 实体对象的反射操作
*
* @param <T>
*/
public class EntityOperation<T> {
private Logger log = Logger.getLogger(EntityOperation.class);
public Class<T> entityClass = null; // 泛型实体Class对象
public final Map<String, PropertyMapping> mappings;
public final RowMapper<T> rowMapper;

public final String tableName;
public String allColumn = "*";
public Field pkField;

public EntityOperation(Class<T> clazz,String pk) throws Exception{
if(!clazz.isAnnotationPresent(Entity.class)){
throw new Exception("在" + clazz.getName() + "中没有找到Entity注解，不能做ORM映射");
}
this.entityClass = clazz;
Table table = entityClass.getAnnotation(Table.class);
if (table != null) {
this.tableName = table.name();
} else {
this.tableName =  entityClass.getSimpleName();
}
Map<String, Method> getters = ClassMappings.findPublicGetters(entityClass);
Map<String, Method> setters = ClassMappings.findPublicSetters(entityClass);
Field[] fields = ClassMappings.findFields(entityClass);
fillPkFieldAndAllColumn(pk,fields);
this.mappings = getPropertyMappings(getters, setters, fields);
this.allColumn = this.mappings.keySet().toString().replace("[", "").replace("]",""). replaceAll(" ","");
this.rowMapper = createRowMapper();
}

Map<String, PropertyMapping> getPropertyMappings(Map<String, Method> getters, Map<String, Method> setters, Field[] fields) {
Map<String, PropertyMapping> mappings = new HashMap<String, PropertyMapping>();
String name;
for (Field field : fields) {
if (field.isAnnotationPresent(Transient.class))
continue;
name = field.getName();
if(name.startsWith("is")){
name = name.substring(2);
}
name = Character.toLowerCase(name.charAt(0)) + name.substring(1);
Method setter = setters.get(name);
Method getter = getters.get(name);
if (setter == null || getter == null){
continue;
}
Column column = field.getAnnotation(Column.class);
if (column == null) {
mappings.put(field.getName(), new PropertyMapping(getter, setter, field));
} else {
mappings.put(column.name(), new PropertyMapping(getter, setter, field));
}
}
return mappings;
}

RowMapper<T> createRowMapper() {
return new RowMapper<T>() {
public T mapRow(ResultSet rs, int rowNum) throws SQLException {
try {
T t = entityClass.newInstance();
ResultSetMetaData meta = rs.getMetaData();
int columns = meta.getColumnCount();
String columnName;
for (int i = 1; i <= columns; i++) {
Object value = rs.getObject(i);
columnName = meta.getColumnName(i);
fillBeanFieldValue(t,columnName,value);
}
return t;
}catch (Exception e) {
throw new RuntimeException(e);
}
}
};
}

protected void fillBeanFieldValue(T t, String columnName, Object value) {
if (value != null) {
PropertyMapping pm = mappings.get(columnName);
if (pm != null) {
try {
pm.set(t, value);
} catch (Exception e) {
e.printStackTrace();
}
}
}
}

private void fillPkFieldAndAllColumn(String pk, Field[] fields) {
//设定主键
try {
if(!StringUtils.isEmpty(pk)){
pkField = entityClass.getDeclaredField(pk);
pkField.setAccessible(true);
}
} catch (Exception e) {
log.debug("没找到主键列，主键列名必须与属性名相同");
}
for (int i = 0 ; i < fields.length ;i ++) {
Field f = fields[i];
if(StringUtils.isEmpty(pk)){
Id id = f.getAnnotation(Id.class);
if(id != null){
pkField = f;
break;
}
}
}
}

public T parse(ResultSet rs) {
T t = null;
if (null == rs) {
return null;
}
Object value = null;
try {
t = (T) entityClass.newInstance();
for (String columnName : mappings.keySet()) {
try {
value = rs.getObject(columnName);
} catch (Exception e) {
e.printStackTrace();
}
fillBeanFieldValue(t,columnName,value);
}
} catch (Exception ex) {
ex.printStackTrace();
}
return t;
}

public Map<String, Object> parse(T t) {
Map<String, Object> _map = new TreeMap<String, Object>();
try {

for (String columnName : mappings.keySet()) {
Object value = mappings.get(columnName).getter.invoke(t);
if (value == null)
continue;
_map.put(columnName, value);

}
} catch (Exception e) {
e.printStackTrace();
}
return _map;
}

public void println(T t) {
try {
for (String columnName : mappings.keySet()) {
Object value = mappings.get(columnName).getter.invoke(t);
if (value == null)
continue;
System.out.println(columnName + " = " + value);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}

class PropertyMapping {

final boolean insertable;
final boolean updatable;
final String columnName;
final boolean id;
final Method getter;
final Method setter;
final Class enumClass;
final String fieldName;

public PropertyMapping(Method getter, Method setter, Field field) {
this.getter = getter;
this.setter = setter;
this.enumClass = getter.getReturnType().isEnum() ? getter.getReturnType() : null;
Column column = field.getAnnotation(Column.class);
this.insertable = column == null || column.insertable();
this.updatable = column == null || column.updatable();
this.columnName = column == null ? ClassMappings.getGetterName(getter) : ("".equals(column.name()) ? ClassMappings.getGetterName(getter) : column.name());
this.id = field.isAnnotationPresent(Id.class);
this.fieldName = field.getName();
}

@SuppressWarnings("unchecked")
Object get(Object target) throws Exception {
Object r = getter.invoke(target);
return enumClass == null ? r : Enum.valueOf(enumClass, (String) r);
}

@SuppressWarnings("unchecked")
void set(Object target, Object value) throws Exception {
if (enumClass != null && value != null) {
value = Enum.valueOf(enumClass, (String) value);
}
//BeanUtils.setProperty(target, fieldName, value);
try {
if(value != null){
setter.invoke(target, setter.getParameterTypes()[0].cast(value));
}
} catch (Exception e) {
e.printStackTrace();
/**
* 出错原因如果是boolean字段、mysql字段类型，设置tinyint(1)
*/
System.err.println(fieldName + "--" + value);
}

}
}

3.3 QueryRuleSqlBuilder

QueryRuleSqlBuilder根据用户构建好的QueryRule来自动生成SQL语句，代码如下：

package com.tom.orm.framework;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.commons.lang.ArrayUtils;
import com.tom.orm.framework.QueryRule.Rule;
import javax.core.common.utils.StringUtils;

/**
* 根据QueryRule自动构建SQL语句
*/
public class QueryRuleSqlBuilder {

private int CURR_INDEX = 0; //记录参数所在的位置
private List<String> properties; //保存列名列表
private List<Object> values; //保存参数值列表
private List<Order> orders; //保存排序规则列表

private String whereSql = "";
private String orderSql = "";
private Object [] valueArr = new Object[]{};
private Map<Object,Object> valueMap = new HashMap<Object,Object>();

/**
* 获得查询条件
* @return
*/
public String getWhereSql(){
return this.whereSql;
}

/**
* 获得排序条件
* @return
*/
public String getOrderSql(){
return this.orderSql;
}

/**
* 获得参数值列表
* @return
*/
public Object [] getValues(){
return this.valueArr;
}

/**
* 获取参数列表
* @return
*/
public Map<Object,Object> getValueMap(){
return this.valueMap;
}

/**
* 创建SQL构造器
* @param queryRule
*/
public  QueryRuleSqlBuilder(QueryRule queryRule) {
CURR_INDEX = 0;
properties = new ArrayList<String>();
values = new ArrayList<Object>();
orders = new ArrayList<Order>();
for (QueryRule.Rule rule : queryRule.getRuleList()) {
switch (rule.getType()) {
case QueryRule.BETWEEN:
processBetween(rule);
break;
case QueryRule.EQ:
processEqual(rule);
break;
case QueryRule.LIKE:
processLike(rule);
break;
case QueryRule.NOTEQ:
processNotEqual(rule);
break;
case QueryRule.GT:
processGreaterThen(rule);
break;
case QueryRule.GE:
processGreaterEqual(rule);
break;
case QueryRule.LT:
processLessThen(rule);
break;
case QueryRule.LE:
processLessEqual(rule);
break;
case QueryRule.IN:
processIN(rule);
break;
case QueryRule.NOTIN:
processNotIN(rule);
break;
case QueryRule.ISNULL:
processIsNull(rule);
break;
case QueryRule.ISNOTNULL:
processIsNotNull(rule);
break;
case QueryRule.ISEMPTY:
processIsEmpty(rule);
break;
case QueryRule.ISNOTEMPTY:
processIsNotEmpty(rule);
break;
case QueryRule.ASC_ORDER:
processOrder(rule);
break;
case QueryRule.DESC_ORDER:
processOrder(rule);
break;
default:
throw new IllegalArgumentException("type " + rule.getType() + " not supported.");
}
}
//拼装where语句
appendWhereSql();
//拼装排序语句
appendOrderSql();
//拼装参数值
appendValues();
}

/**
* 去掉order
*
* @param sql
* @return
*/
protected String removeOrders(String sql) {
Pattern p = Pattern.compile("order\\s*by[\\w|\\W|\\s|\\S]*", Pattern.CASE_INSENSITIVE);
Matcher m = p.matcher(sql);
StringBuffer sb = new StringBuffer();
while (m.find()) {
m.appendReplacement(sb, "");
}
m.appendTail(sb);
return sb.toString();
}

/**
* 去掉select
*
* @param sql
* @return
*/
protected String removeSelect(String sql) {
if(sql.toLowerCase().matches("from\\s+")){
int beginPos = sql.toLowerCase().indexOf("from");
return sql.substring(beginPos);
}else{
return sql;
}
}

/**
* 处理like
* @param rule
*/
private  void processLike(QueryRule.Rule rule) {
if (ArrayUtils.isEmpty(rule.getValues())) {
return;
}
Object obj = rule.getValues()[0];

if (obj != null) {
String value = obj.toString();
if (!StringUtils.isEmpty(value)) {
value = value.replace('*', '%');
obj = value;
}
}
add(rule.getAndOr(),rule.getPropertyName(),"like","%"+rule.getValues()[0]+"%");
}

/**
* 处理between
* @param rule
*/
private  void processBetween(QueryRule.Rule rule) {
if ((ArrayUtils.isEmpty(rule.getValues()))
|| (rule.getValues().length < 2)) {
return;
}
add(rule.getAndOr(),rule.getPropertyName(),"","between",rule.getValues()[0],"and");
add(0,"","","",rule.getValues()[1],"");
}

/**
* 处理 =
* @param rule
*/
private  void processEqual(QueryRule.Rule rule) {
if (ArrayUtils.isEmpty(rule.getValues())) {
return;
}
add(rule.getAndOr(),rule.getPropertyName(),"=",rule.getValues()[0]);
}

/**
* 处理 <>
* @param rule
*/
private  void processNotEqual(QueryRule.Rule rule) {
if (ArrayUtils.isEmpty(rule.getValues())) {
return;
}
add(rule.getAndOr(),rule.getPropertyName(),"<>",rule.getValues()[0]);
}

/**
* 处理 >
* @param rule
*/
private  void processGreaterThen(
QueryRule.Rule rule) {
if (ArrayUtils.isEmpty(rule.getValues())) {
return;
}
add(rule.getAndOr(),rule.getPropertyName(),">",rule.getValues()[0]);
}

/**
* 处理>=
* @param rule
*/
private  void processGreaterEqual(
QueryRule.Rule rule) {
if (ArrayUtils.isEmpty(rule.getValues())) {
return;
}
add(rule.getAndOr(),rule.getPropertyName(),">=",rule.getValues()[0]);
}

/**
* 处理<
* @param rule
*/
private  void processLessThen(QueryRule.Rule rule) {
if (ArrayUtils.isEmpty(rule.getValues())) {
return;
}
add(rule.getAndOr(),rule.getPropertyName(),"<",rule.getValues()[0]);
}

/**
* 处理<=
* @param rule
*/
private  void processLessEqual(
QueryRule.Rule rule) {
if (ArrayUtils.isEmpty(rule.getValues())) {
return;
}
add(rule.getAndOr(),rule.getPropertyName(),"<=",rule.getValues()[0]);
}

/**
* 处理  is null
* @param rule
*/
private  void processIsNull(QueryRule.Rule rule) {
add(rule.getAndOr(),rule.getPropertyName(),"is null",null);
}

/**
* 处理 is not null
* @param rule
*/
private  void processIsNotNull(QueryRule.Rule rule) {
add(rule.getAndOr(),rule.getPropertyName(),"is not null",null);
}

/**
* 处理  <>''
* @param rule
*/
private  void processIsNotEmpty(QueryRule.Rule rule) {
add(rule.getAndOr(),rule.getPropertyName(),"<>","''");
}

/**
* 处理 =''
* @param rule
*/
private  void processIsEmpty(QueryRule.Rule rule) {
add(rule.getAndOr(),rule.getPropertyName(),"=","''");
}

/**
* 处理in和not in
* @param rule
* @param name
*/
private void inAndNotIn(QueryRule.Rule rule,String name){
if (ArrayUtils.isEmpty(rule.getValues())) {
return;
}
if ((rule.getValues().length == 1) && (rule.getValues()[0] != null)
&& (rule.getValues()[0] instanceof List)) {
List<Object> list = (List) rule.getValues()[0];

if ((list != null) && (list.size() > 0)){
for (int i = 0; i < list.size(); i++) {
if(i == 0 && i == list.size() - 1){
add(rule.getAndOr(),rule.getPropertyName(),"",name + " (",list.get(i),")");
}else if(i == 0 && i < list.size() - 1){
add(rule.getAndOr(),rule.getPropertyName(),"",name + " (",list.get(i),"");
}
if(i > 0 && i < list.size() - 1){
add(0,"",",","",list.get(i),"");
}
if(i == list.size() - 1 && i != 0){
add(0,"",",","",list.get(i),")");
}
}
}
} else {
Object[] list =  rule.getValues();
for (int i = 0; i < list.length; i++) {
if(i == 0 && i == list.length - 1){
add(rule.getAndOr(),rule.getPropertyName(),"",name + " (",list[i],")");
}else if(i == 0 && i < list.length - 1){
add(rule.getAndOr(),rule.getPropertyName(),"",name + " (",list[i],"");
}
if(i > 0 && i < list.length - 1){
add(0,"",",","",list[i],"");
}
if(i == list.length - 1 && i != 0){
add(0,"",",","",list[i],")");
}
}
}
}

/**
* 处理 not in
* @param rule
*/
private void processNotIN(QueryRule.Rule rule){
inAndNotIn(rule,"not in");
}

/**
* 处理 in
* @param rule
*/
private  void processIN(QueryRule.Rule rule) {
inAndNotIn(rule,"in");
}

/**
* 处理 order by
* @param rule 查询规则
*/
private void processOrder(Rule rule) {
switch (rule.getType()) {
case QueryRule.ASC_ORDER:
//propertyName非空
if (!StringUtils.isEmpty(rule.getPropertyName())) {
orders.add(Order.asc(rule.getPropertyName()));
}
break;
case QueryRule.DESC_ORDER:
//propertyName非空
if (!StringUtils.isEmpty(rule.getPropertyName())) {
orders.add(Order.desc(rule.getPropertyName()));
}
break;
default:
break;
}
}

/**
* 加入SQL查询规则队列
* @param andOr and 或者 or
* @param key 列名
* @param split 列名与值之间的间隔
* @param value 值
*/
private  void add(int andOr,String key,String split ,Object value){
add(andOr,key,split,"",value,"");
}

/**
* 加入SQL查询规则队列
* @param andOr and 或则 or
* @param key 列名
* @param split 列名与值之间的间隔
* @param prefix 值前缀
* @param value 值
* @param suffix 值后缀
*/
private void add(int andOr,String key,String split,String prefix,Object value,String suffix){
String andOrStr = (0 == andOr ? "" :(QueryRule.AND == andOr ? " and " : " or "));
properties.add(CURR_INDEX, andOrStr + key + " " + split + prefix + (null != value ? " ? " : " ") + suffix);
if(null != value){
values.add(CURR_INDEX,value);
CURR_INDEX ++;
}
}

/**
* 拼装 where 语句
*/
private void appendWhereSql(){
StringBuffer whereSql = new StringBuffer();
for (String p : properties) {
whereSql.append(p);
}
this.whereSql = removeSelect(removeOrders(whereSql.toString()));
}

/**
* 拼装排序语句
*/
private void appendOrderSql(){
StringBuffer orderSql = new StringBuffer();
for (int i = 0 ; i < orders.size(); i ++) {
if(i > 0 && i < orders.size()){
orderSql.append(",");
}
orderSql.append(orders.get(i).toString());
}
this.orderSql = removeSelect(removeOrders(orderSql.toString()));
}

/**
* 拼装参数值
*/
private void appendValues(){
Object [] val = new Object[values.size()];
for (int i = 0; i < values.size(); i ++) {
val[i] = values.get(i);
valueMap.put(i, values.get(i));
}
this.valueArr = val;
}
}

3.4 BaseDaoSupport

BaseDaoSupport主要是对JdbcTemplate的包装，下面讲一下其重要代码，请“小伙伴们” 关 注『 Tom弹架构 』可下载全部源代码。先看全局定义：

package com.tom.orm.framework;

...

/**
* BaseDao 扩展类，主要功能是支持自动拼装SQL语句，必须继承方可使用
* @author Tom
*/
public abstract class BaseDaoSupport<T extends Serializable, PK extends Serializable> implements BaseDao<T,PK> {
private Logger log = Logger.getLogger(BaseDaoSupport.class);

private String tableName = "";

private JdbcTemplate jdbcTemplateWrite;
private JdbcTemplate jdbcTemplateReadOnly;

private DataSource dataSourceReadOnly;
private DataSource dataSourceWrite;

private EntityOperation<T> op;

@SuppressWarnings("unchecked")
protected BaseDaoSupport(){
try{
Class<T> entityClass = GenericsUtils.getSuperClassGenricType(getClass(), 0);
op = new EntityOperation<T>(entityClass,this.getPKColumn());
this.setTableName(op.tableName);
}catch(Exception e){
e.printStackTrace();
}
}

protected String getTableName() { return tableName; }
protected DataSource getDataSourceReadOnly() { return dataSourceReadOnly;  }
protected DataSource getDataSourceWrite() { return dataSourceWrite;  }

/**
* 动态切换表名
*/
protected void setTableName(String tableName) {
if(StringUtils.isEmpty(tableName)){
this.tableName = op.tableName;
}else{
this.tableName = tableName;
}
}

protected void setDataSourceWrite(DataSource dataSourceWrite) {
this.dataSourceWrite = dataSourceWrite;
jdbcTemplateWrite = new JdbcTemplate(dataSourceWrite);
}

protected void setDataSourceReadOnly(DataSource dataSourceReadOnly) {
this.dataSourceReadOnly = dataSourceReadOnly;
jdbcTemplateReadOnly = new JdbcTemplate(dataSourceReadOnly);
}

private JdbcTemplate jdbcTemplateReadOnly() {
return this.jdbcTemplateReadOnly;
}

private JdbcTemplate jdbcTemplateWrite() {
return this.jdbcTemplateWrite;
}

/**
* 还原默认表名
*/
protected void restoreTableName(){ this.setTableName(op.tableName);  }

/**
* 获取主键列名称，建议子类重写
* @return
*/
protected abstract String getPKColumn();

protected abstract void setDataSource(DataSource dataSource);

//此处有省略

}

为了照顾程序员的一般使用习惯，查询方法的前缀命名主要有select、get、load，兼顾Hibernate和MyBatis的命名风格。

/**
* 查询函数，使用查询规则
* 例如以下代码查询条件为匹配的数据
*
* @param queryRule 查询规则
* @return 查询的结果List
*/
public List<T> select(QueryRule queryRule) throws Exception{
QueryRuleSqlBuilder bulider = new QueryRuleSqlBuilder(queryRule);
String ws = removeFirstAnd(bulider.getWhereSql());
String whereSql = ("".equals(ws) ? ws : (" where " + ws));
String sql = "select " + op.allColumn + " from " + getTableName() + whereSql;
Object [] values = bulider.getValues();
String orderSql = bulider.getOrderSql();
orderSql = (StringUtils.isEmpty(orderSql) ? " " : (" order by " + orderSql));
sql += orderSql;
log.debug(sql);
return (List<T>) this.jdbcTemplateReadOnly().query(sql, this.op.rowMapper, values);
}

...

/**
* 根据SQL语句执行查询，参数为Object数组对象
* @param sql 查询语句
* @param args 为Object数组
* @return 符合条件的所有对象
*/
public List<Map<String,Object>> selectBySql(String sql,Object... args) throws Exception{
return this.jdbcTemplateReadOnly().queryForList(sql,args);
}

...

/**
* 分页查询函数，使用查询规则<br>
* 例如以下代码查询条件为匹配的数据
*
* @param queryRule 查询规则
* @param pageNo 页号，从1开始
* @param pageSize 每页的记录条数
* @return 查询的结果Page
*/
public Page<T> select(QueryRule queryRule,final int pageNo, final int pageSize) throws Exception{
QueryRuleSqlBuilder bulider = new QueryRuleSqlBuilder(queryRule);
Object [] values = bulider.getValues();
String ws = removeFirstAnd(bulider.getWhereSql());
String whereSql = ("".equals(ws) ? ws : (" where " + ws));
String countSql = "select count(1) from " + getTableName() + whereSql;
long count = (Long) this.jdbcTemplateReadOnly().queryForMap(countSql, values).get ("count(1)");
if (count == 0) {
return new Page<T>();
}
long start = (pageNo - 1) * pageSize;
//在有数据的情况下，继续查询
String orderSql = bulider.getOrderSql();
orderSql = (StringUtils.isEmpty(orderSql) ? " " : (" order by " + orderSql));
String sql = "select " + op.allColumn +" from " + getTableName() + whereSql + orderSql + " limit " + start + "," + pageSize;
List<T> list = (List<T>) this.jdbcTemplateReadOnly().query(sql, this.op.rowMapper, values);
log.debug(sql);
return new Page<T>(start, count, pageSize, list);
}
...

/**
* 分页查询特殊SQL语句
* @param sql 语句
* @param param  查询条件
* @param pageNo   页码
* @param pageSize 每页内容
* @return
*/
public Page<Map<String,Object>> selectBySqlToPage(String sql, Object [] param, final int pageNo, final int pageSize) throws Exception {
String countSql = "select count(1) from (" + sql + ") a";

long count = (Long) this.jdbcTemplateReadOnly().queryForMap(countSql,param).get("count(1)");
if (count == 0) {
return new Page<Map<String,Object>>();
}
long start = (pageNo - 1) * pageSize;
sql = sql + " limit " + start + "," + pageSize;
List<Map<String,Object>> list = (List<Map<String,Object>>) this.jdbcTemplateReadOnly(). queryForList(sql, param);
log.debug(sql);
return new Page<Map<String,Object>>(start, count, pageSize, list);
}

/**
* 获取默认的实例对象
* @param <T>
* @param pkValue
* @param rowMapper
* @return
*/
private <T> T doLoad(Object pkValue, RowMapper<T> rowMapper){
Object obj = this.doLoad(getTableName(), getPKColumn(), pkValue, rowMapper);
if(obj != null){
return (T)obj;
}
return null;
}

插入方法，均以insert开头：

/**
* 插入并返回ID
* @param entity
* @return
*/
public PK insertAndReturnId(T entity) throws Exception{
return (PK)this.doInsertRuturnKey(parse(entity));
}

/**
* 插入一条记录
* @param entity
* @return
*/
public boolean insert(T entity) throws Exception{
return this.doInsert(parse(entity));
}
/**
* 批量保存对象.<br>
*
* @param list 待保存的对象List
* @throws InvocationTargetException
* @throws IllegalArgumentException
* @throws IllegalAccessException
*/
public int insertAll(List<T> list) throws Exception {
int count = 0 ,len = list.size(),step = 50000;
Map<String, PropertyMapping> pm = op.mappings;
int maxPage = (len % step == 0) ? (len / step) : (len / step + 1);
for (int i = 1; i <= maxPage; i ++) {
Page<T> page = pagination(list, i, step);
String sql = "insert into " + getTableName() + "(" + op.allColumn + ") values ";// (" + valstr.toString() + ")";
StringBuffer valstr = new StringBuffer();
Object[] values = new Object[pm.size() * page.getRows().size()];
for (int j = 0; j < page.getRows().size(); j ++) {
if(j > 0 && j < page.getRows().size()){ valstr.append(","); }
valstr.append("(");
int k = 0;
for (PropertyMapping p : pm.values()) {
values[(j * pm.size()) + k] = p.getter.invoke(page.getRows().get(j));
if(k > 0 && k < pm.size()){ valstr.append(","); }
valstr.append("?");
k ++;
}
valstr.append(")");
}
int result = jdbcTemplateWrite().update(sql + valstr.toString(), values);
count += result;
}

return count;
}

private Serializable doInsertRuturnKey(Map<String,Object> params){
final List<Object> values = new ArrayList<Object>();
final String sql = makeSimpleInsertSql(getTableName(),params,values);
KeyHolder keyHolder = new GeneratedKeyHolder();
final JdbcTemplate jdbcTemplate = new JdbcTemplate(getDataSourceWrite());
try {

jdbcTemplate.update(new PreparedStatementCreator() {
public PreparedStatement createPreparedStatement(

Connection con) throws SQLException {
PreparedStatement ps = con.prepareStatement(sql,Statement.RETURN_GENERATED_KEYS);

for (int i = 0; i < values.size(); i++) {
ps.setObject(i+1, values.get(i)==null?null:values.get(i));

}
return ps;
}

}, keyHolder);
} catch (DataAccessException e) {
log.error("error",e);
}

if (keyHolder == null) { return ""; }

Map<String, Object> keys = keyHolder.getKeys();
if (keys == null || keys.size() == 0 || keys.values().size() == 0) {
return "";
}
Object key = keys.values().toArray()[0];
if (key == null || !(key instanceof Serializable)) {
return "";
}
if (key instanceof Number) {
//Long k = (Long) key;
Class clazz = key.getClass();
//       return clazz.cast(key);
return (clazz == int.class || clazz == Integer.class) ? ((Number) key).intValue() : ((Number)key).longValue();

} else if (key instanceof String) {
return (String) key;
} else {
return (Serializable) key;
}

}

/**
* 插入
* @param params
* @return
*/
private boolean doInsert(Map<String, Object> params) {
String sql = this.makeSimpleInsertSql(this.getTableName(), params);
int ret = this.jdbcTemplateWrite().update(sql, params.values().toArray());
return ret > 0;
}

删除方法，均以delete开头：

/**
* 删除对象.<br>
*
* @param entity 待删除的实体对象
*/
public boolean delete(T entity) throws Exception {
return this.doDelete(op.pkField.get(entity)) > 0;
}

/**
* 删除对象.<br>
*
* @param list 待删除的实体对象列表
* @throws InvocationTargetException
* @throws IllegalArgumentException
* @throws IllegalAccessException
*/
public int deleteAll(List<T> list) throws Exception {
String pkName = op.pkField.getName();
int count = 0 ,len = list.size(),step = 1000;
Map<String, PropertyMapping> pm = op.mappings;
int maxPage = (len % step == 0) ? (len / step) : (len / step + 1);
for (int i = 1; i <= maxPage; i ++) {
StringBuffer valstr = new StringBuffer();
Page<T> page = pagination(list, i, step);
Object[] values = new Object[page.getRows().size()];

for (int j = 0; j < page.getRows().size(); j ++) {
if(j > 0 && j < page.getRows().size()){ valstr.append(","); }
values[j] = pm.get(pkName).getter.invoke(page.getRows().get(j));
valstr.append("?");
}

String sql = "delete from " + getTableName() + " where " + pkName + " in (" + valstr.toString() + ")";
int result = jdbcTemplateWrite().update(sql, values);
count += result;
}
return count;
}

/**
* 根据id删除对象。如果有记录则删之，没有记录也不报异常<br>
* 例如：删除主键唯一的记录
*
* @param id 序列化id
*/
protected void deleteByPK(PK id)  throws Exception {
this.doDelete(id);
}

/**
* 删除实例对象，返回删除记录数
* @param tableName
* @param pkName
* @param pkValue
* @return
*/
private int doDelete(String tableName, String pkName, Object pkValue) {
StringBuffer sb = new StringBuffer();
sb.append("delete from ").append(tableName).append(" where ").append(pkName).append(" = ?");
int ret = this.jdbcTemplateWrite().update(sb.toString(), pkValue);
return ret;
}

修改方法，均以update开头：

/**
* 更新对象.<br>
*
* @param entity 待更新对象
* @throws IllegalAccessException
* @throws IllegalArgumentException
*/
public boolean update(T entity) throws Exception {
return this.doUpdate(op.pkField.get(entity), parse(entity)) > 0;
}

/**
* 更新实例对象，返回删除记录数
* @param pkValue
* @param params
* @return
*/
private int doUpdate(Object pkValue, Map<String, Object> params){
String sql = this.makeDefaultSimpleUpdateSql(pkValue, params);
params.put(this.getPKColumn(), pkValue);
int ret = this.jdbcTemplateWrite().update(sql, params.values().toArray());
return ret;
}

至此一个完整的ORM框架就横空出世。当然，还有很多优化的地方，请小伙伴可以继续完善。

原创不易，坚持很酷，都看到这里了，小伙伴记得点赞、收藏、在看，一键三连加关注！如果你觉得内容太干，可以分享转发给朋友滋润滋润！