Mybatis基于注解形式的sql语句生成

借鉴博客网址:http://blog.csdn.net/hj7jay/article/details/51907652.

对其做了些优化，但此种sql生成方式仅适用于复杂程度不高的sql，所以实用性不是很高，仅仅是写着玩的，知道点mybatis的注解形式的使用方式，可能以后会逐渐完善起来。第一次写博客，写的简单点。

package com.bob.config.mvc.mybatis;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
* 实体类对应的列
*
* @author jjb
* @create 2017-09-08 14:42
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD, ElementType.METHOD})
public @interface Column {

/**
* 当前属性对应的列名
*
* @return
*/
String value() default "";

/**
* 当前属性是不是表必须的
*
* @return
*/
boolean required() default true;

}

package com.bob.config.mvc.mybatis;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
* 实体类对应的表
*
* @author jjb
* @create 2017-09-08 14:44
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE})
public @interface Table {

String value() default "";

/**
* 当前表的主键
*
* @return
*/
String key();

}

package com.bob.config.mvc.mybatis;

import org.apache.ibatis.annotations.DeleteProvider;
import org.apache.ibatis.annotations.InsertProvider;
import org.apache.ibatis.annotations.Options;
import org.apache.ibatis.annotations.SelectProvider;
import org.apache.ibatis.annotations.UpdateProvider;

/**
* Mybatis基础Mapper
*
* @author jjb
* @create 2017-09-08 14:37
*/
public interface BaseMapper<T> {

/**
* 插入语句
*
* @param bean
* @return
*/
@Options(useGeneratedKeys = true)
@InsertProvider(type = SqlProvider.class, method = "insert")
public int insert(T bean);

/**
* 删除语句
*
* @param bean
* @return
*/
@DeleteProvider(type = SqlProvider.class, method = "delete")
public int delete(T bean);

/**
* 更新语句
*
* @param bean
* @return
*/
@UpdateProvider(type = SqlProvider.class, method = "update")
public int update(T bean);

/**
* 查找语句
*
* @param bean
* @return
*/
@SelectProvider(type = SqlProvider.class, method = "select")
public T findFirst(T bean);

}

package com.bob.config.mvc.mybatis;

import java.time.LocalDate;

/**
* Mybatis实体类
*
* @author jjb
* @create 2017-09-08 17:16
*/
@Table(key = "id")
public class MybatisEntity {

@Column()
private String id;
@Column("USER_NAME")
private String name;
@Column()
private Integer age;

private LocalDate date;
@Column("ADRESS_NUMBER")
private Integer userAdressNumber;

public String getId() {
return id;
}

public void setId(String id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public Integer getAge() {
return age;
}

public void setAge(Integer age) {
this.age = age;
}

@Column("CUR_DATE")
public LocalDate getDate() {
return date;
}

public void setDate(LocalDate date) {
this.date = date;
}

public Integer getUserAdressNumber() {
return userAdressNumber;
}

public void setUserAdressNumber(Integer userAdressNumber) {
this.userAdressNumber = userAdressNumber;
}
}

package com.bob.config.mvc.mybatis;

import java.lang.reflect.Field;
import java.util.Map;

/**
* 表到实体的格式化器
*
* @author jjb
* @create 2017-09-08 14:51
*/
public interface TableFormatter {

/**
* 根据属性获取字段名称
*
* @param field
* @return
*/
public String getColumnName(Field field);

/**
* 获取主键属性对应的列名
*
* @return
*/
public String getKeyColumnName(Class<?> clazz);

/**
* 获取主键的属性名称
*
* @param clazz
* @return
*/
public String getKeyFiledName(Class<?> clazz);

/**
* 根据类获取表名称
*
* @param clazz
* @return
*/
public String getTableName(Class<?> clazz);

/**
* 获取一个类的所有属性的映射信息
*
* @param clazz
* @return
*/
public Map<Field, String> getFieldMappings(Class<?> clazz);

}

package com.bob.config.mvc.mybatis;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.HashMap;
import java.util.Map;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeanUtils;
import org.springframework.stereotype.Component;
import org.springframework.util.Assert;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.StringUtils;

/**
* 依据驼峰原则来将表的信息格式化为实体类的信息，在驼峰处改小写同时插入下划线
*
* @author jjb
* @create 2017-09-08 14:55
*/
@Component
public class HumpToUnderLineFormatter implements TableFormatter {

private static final Logger LOGGER = LoggerFactory.getLogger(HumpToUnderLineFormatter.class);

private static final Map<Class<?>, Map<Field, String>> FIELD_TO_COLUMN_MAPPINGS = new HashMap<Class<?>, Map<Field, String>>();

private static final Map<Class, String> CLASS_TO_TABLE_MAPPING = new HashMap<Class, String>();

private static final StringBuilder SB = new StringBuilder();

private static final Object LOCK = new Object();

@Override
public String getColumnName(Field field) {
Assert.notNull(field, "属性不能为空");
Map<Field, String> mappings = FIELD_TO_COLUMN_MAPPINGS.get(field.getDeclaringClass());
if (mappings == null) {
synchronized (LOCK) {
mappings = FIELD_TO_COLUMN_MAPPINGS.get(field.getDeclaringClass());
if (mappings == null) {
mappings = buildMapping(field.getDeclaringClass());
}
}
}
return mappings.get(field);
}

@Override
public String getKeyColumnName(Class<?> clazz) {
Table table = checkClass(clazz);
return getColumnName(ReflectionUtils.findField(clazz,table.key()));
}

@Override
public String getKeyFiledName(Class<?> clazz) {
Table table = checkClass(clazz);
Field field = ReflectionUtils.findField(clazz,table.key());
Assert.state(field != null,"@Table的key()指定的属性必须存在");
return field.getName();
}

private Table checkClass(Class<?> clazz){
Assert.isTrue(clazz != null , "与Table对应的Class不能为空");
Table table = clazz.getAnnotation(Table.class);
Assert.isTrue(table != null && StringUtils.hasText(table.key()),"["+clazz.getName()+"]必须标识@Table注解且key()不能为空");
return table;
}

@Override
public String getTableName(Class<?> clazz) {
Assert.notNull(clazz, "类不能为空");
Assert.isTrue(clazz.isAnnotationPresent(Table.class), "[" + clazz.getName() + "]类上必须含有@Table注解");
String name = CLASS_TO_TABLE_MAPPING.get(clazz);
if (name == null) {
synchronized (LOCK) {
name = CLASS_TO_TABLE_MAPPING.get(clazz);
if (name == null) {
buildMapping(clazz);
}
}
}
return CLASS_TO_TABLE_MAPPING.get(clazz);
}

@Override
public Map<Field, String> getFieldMappings(Class<?> clazz) {
Assert.isTrue(clazz != null && clazz.isAnnotationPresent(Table.class), "与Table对应的Class不能为空且必须标识@Table注解");
Map<Field, String> mappings = FIELD_TO_COLUMN_MAPPINGS.get(clazz);
if (mappings == null) {
synchronized (LOCK) {
mappings = FIELD_TO_COLUMN_MAPPINGS.get(clazz);
if (mappings == null) {
mappings = buildMapping(clazz);
}
}
}
return FIELD_TO_COLUMN_MAPPINGS.get(clazz);
}

/**
* 创建实体到表映射
*
* @param clazz
*/
private Map<Field, String> buildMapping(Class<?> clazz) {
buildClassToTableMapping(clazz);
Map<Field, String> mappings = new HashMap<Field, String>();
FIELD_TO_COLUMN_MAPPINGS.put(clazz, mappings);
buildFiledToColumnMapping(clazz, mappings);
buildFiledToColumnMappingWithGetter(clazz, mappings);
return mappings;
}

/**
* 创建类名到表名的名称映射
*
* @param clazz
*/
private void buildClassToTableMapping(Class<?> clazz) {
Table table = clazz.getAnnotation(Table.class);
Assert.notNull(table, "[" + clazz.getName() + "]类上必须有@Table注解");
CLASS_TO_TABLE_MAPPING.put(clazz, StringUtils.hasText(table.value()) ? table.value() : doFormatWithHunmRule(clazz.getSimpleName()));
}

/**
* 通过Filed建立属性名称到字段名称的映射
*
* @param clazz
* @param mappings
*/
private void buildFiledToColumnMapping(Class<?> clazz, Map<Field, String> mappings) {
ReflectionUtils.doWithLocalFields(clazz, (field) -> {
Column column = field.getAnnotation(Column.class);
if (column != null) {
if (Modifier.isStatic(field.getModifiers())) {
LOGGER.error("[{}]注解不适用于静态方法:[{}]", Column.class.toString(), field);
return;
}
mappings.put(field, StringUtils.hasText(column.value()) ? column.value() : doFormatWithHunmRule(field.getName()));
}
}
);
}

/**
* 通过getter()建立属性名称到字段名称的映射
*
* @param clazz
* @param mappings
*/
private void buildFiledToColumnMappingWithGetter(Class<?> clazz, Map<Field, String> mappings) {

ReflectionUtils.doWithLocalMethods(clazz, (method) -> {
Column column = method.getAnnotation(Column.class);
if (column != null) {
if (Modifier.isStatic(method.getModifiers())) {
LOGGER.warn("[{}]注解不适用于静态方法: [{}]", Column.class.toString(), method);
return;
}
if (!method.getName().startsWith("get") || method.getParameterTypes().length > 0) {
LOGGER.warn("[{}]注解只适用于getter方法,而非: [{}]方法", Column.class.toString(), method);
return;
}
String fieldName = BeanUtils.findPropertyForMethod(method).getName();
mappings.put(ReflectionUtils.findField(clazz, fieldName),
StringUtils.hasText(column.value()) ? column.value() : doFormatWithHunmRule(fieldName));
}
}
);

}

/**
* 依据驼峰原则格式化属性或者类名称,在驼峰处改小写同时前一位插入下划线,忽略首字母
*
* @param name
* @return
*/
private static String doFormatWithHunmRule(String name) {
Assert.hasText(name, "属性或者类名称不能为空");
SB.delete(0, SB.length());
SB.append(toUpperCase(name.charAt(0)));
for (int i = 1; i < name.length(); i++) {
if (isUpperCase(name.charAt(i))) {
SB.append("_");
}
SB.append(toUpperCase(name.charAt(i)));
}
return SB.toString();
}

/**
* 将字符转换为大写
*
* @param ch
* @return
*/
private static char toUpperCase(char ch) {
return Character.toUpperCase(ch);
}

/**
* 判断是否为大写
*
* @param ch
* @return
*/
private static boolean isUpperCase(char ch) {
return Character.isUpperCase(ch);
}

}

package com.bob.config.mvc.mybatis;

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;
import java.util.Map.Entry;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.StringUtils;

/**
* Mybatis的SQL语句供应器
*
* @author jjb
* @create 2017-09-08 14:37
*/
public class SqlProvider {

private static final Logger LOGGER = LoggerFactory.getLogger(SqlProvider.class);

private TableFormatter tableFormat = new HumpToUnderLineFormatter();

/**
* 根据Bean对象生成插入SQL语句
*
* @param bean
* @return
*/
public String insert(Object bean) {
Class<?> beanClass = bean.getClass();
String tableName = tableFormat.getTableName(beanClass);
StringBuilder insertSql = new StringBuilder();
List<String> columns = new ArrayList<String>();
List<String> values = new ArrayList<String>();
insertSql.append("INSERT INTO ").append(tableName).append("(");
try {
for (Entry<Field, String> entry : tableFormat.getFieldMappings(beanClass).entrySet()) {
Field field = entry.getKey();
field.setAccessible(true);
if (field.get(bean) != null) {
columns.add(entry.getValue());
values.add("#{" + field.getName() + "}");
}
}
} catch (Exception e) {
new RuntimeException("get insert sql has exceptoin:" + e);
}
int columnSize = columns.size();
for (int i = 0; i < columnSize; i++) {
insertSql.append(columns.get(i));
insertSql.append(i != columnSize - 1 ? "," : ") VALUES(");
}
for (int i = 0; i < columnSize; i++) {
insertSql.append(values.get(i));
insertSql.append(i != columnSize - 1 ? "," : ")");
}
return insertSql.toString();
}

/**
* 根据Bean对象生成更新SQL语句
*
* @param bean
* @return
*/
public String update(Object bean) {
Class<?> beanClass = bean.getClass();
String tableName = tableFormat.getTableName(beanClass);
StringBuilder updateSql = new StringBuilder();
updateSql.append(" UPDATE ").append(tableName).append(" SET ");
try {
for (Entry<Field, String> entry : tableFormat.getFieldMappings(beanClass).entrySet()) {
Field field = entry.getKey();
field.setAccessible(true);
if (field.get(bean) != null) {
updateSql.append(entry.getValue()).append("=#{").append(field.getName()).append("},");
}
}
updateSql.deleteCharAt(updateSql.length() - 1);
} catch (Exception e) {
new RuntimeException("get update sql is exceptoin:" + e);
}
updateSql.append(" WHERE ").append(tableFormat.getKeyColumnName(beanClass) + " =#{" + tableFormat.getKeyFiledName(beanClass) + "}");
return updateSql.toString();
}

/**
* 根据Bean对象生成删除SQL语句
*
* @param bean
* @return
*/
public String delete(Object bean) {
Class<?> beanClass = bean.getClass();
String tableName = tableFormat.getTableName(beanClass);
StringBuilder deleteSql = new StringBuilder();
deleteSql.append(" DELETE FROM ").append(tableName).append(" WHERE  ");
try {
for (Entry<Field, String> entry : tableFormat.getFieldMappings(beanClass).entrySet()) {
Field field = entry.getKey();
field.setAccessible(true);
if (field.get(bean) != null) {
deleteSql.append(entry.getValue()).append("=#{").append(field.getName()).append("} AND ");
}
}
deleteSql.delete(deleteSql.length() - 5, deleteSql.length() - 1);
} catch (Exception e) {
new RuntimeException("get delete sql is exceptoin:" + e);
}
return deleteSql.toString();
}

/**
* 生成查询SQL语句
*
* @param bean
* @return
*/
public String select(Object bean) {
Class<?> beanClass = bean.getClass();
String tableName = tableFormat.getTableName(beanClass);
StringBuilder selectSql = new StringBuilder();
List<String> columns = new ArrayList<String>();
List<String> values = new ArrayList<String>();
selectSql.append("SELECT ");
try {
for (Entry<Field, String> entry : tableFormat.getFieldMappings(beanClass).entrySet()) {
Field field = entry.getKey();
field.setAccessible(true);
selectSql.append(entry.getValue() + ",");
if (field.get(bean) != null) {
columns.add(entry.getValue());
values.add("#{" + field.getName() + "}");
}
}
selectSql.deleteCharAt(selectSql.length() - 1);
} catch (Exception e) {
new RuntimeException("get select sql is exceptoin:" + e);
}
selectSql.append(" FROM ").append(tableName).append(" WHERE ");
int columnSize = columns.size();
for (int i = 0; i < columnSize; i++) {
selectSql.append(columns.get(i)).append("=").append(values.get(i)).append(" AND ");
}
selectSql.delete(selectSql.length() - 5, selectSql.length() - 1);
return selectSql.toString();
}

}

package com.bob.test.concrete.mysqlGenerate;

import java.time.LocalDate;

import com.bob.config.mvc.mybatis.MybatisEntity;
import com.bob.config.mvc.mybatis.SqlProvider;
import org.junit.Before;
import org.junit.Test;

/**
* Mysql基于注解形式的sql语句生成测试
*
* @author jjb
* @create 2017-09-11 11:10
*/
public class MysqlGenerateTest {

private SqlProvider sqlProvider;
private MybatisEntity mybatisEntity;

@Before
public void doBefore(){
sqlProvider = new SqlProvider();
mybatisEntity = new MybatisEntity();
mybatisEntity.setId("0015415");
mybatisEntity.setName("lanboal");
mybatisEntity.setAge(28);
mybatisEntity.setDate(LocalDate.now());
mybatisEntity.setUserAdressNumber(24);
}

@Test
public void testInsert(){
String sql = sqlProvider.insert(mybatisEntity);
System.out.println(sql);
}

@Test
public void testUpdate(){
String sql = sqlProvider.update(mybatisEntity);
System.out.println(sql);
}

@Test
public void testDelete(){
String sql = sqlProvider.delete(mybatisEntity);
System.out.println(sql);
}

@Test
public void testSelect(){
String sql = sqlProvider.select(mybatisEntity);
System.out.println(sql);
}

}