Dbutils

package org.byent.dao;
import java.util.List;
import java.util.Map;
/**
* @author Z.ting 2011-8-10 下午07:57:27
*/
public interface Dao {
public <T> List<T> findAll(Class<T> clazz);
public <T> T findById(Class<T> clazz, int id);
public long insert(String sql, Object... args);
public long update(String sql, Object... args);
public List<Map<String, Object>> executeQuery(String sql, Object... args);
public long executeUpdate(String sql, Object... args);
public void delete(String sql, Object... args);
public int[] batchUpdate(String sql, Object[][] objs);
}

这里边就是定义一些CRUD的操作，大家对这个应该不陌生了。现在接口有了，当然需要写一个实现类来完成这个接口所定义的一些工作咯，下面来看下DAO的实现类。

/**
*
*/
package org.byent.dao.impl;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.ResultSetHandler;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.MapListHandler;
import org.apache.log4j.Logger;
import org.byent.dao.Dao;
import com.mysql.jdbc.JDBC4Connection;
import com.mysql.jdbc.jdbc2.optional.MysqlDataSource;
/**
* @author Z.ting 2011-8-10 下午08:05:06
*/
public class DaoImpl implements Dao {
private MysqlDataSource dataSource = new MysqlDataSource();
private QueryRunner qryRun = null;
private Logger logger = Logger.getLogger(getClass());
private java.sql.DatabaseMetaData dbmb;
public DaoImpl() {
dataSource.setUrl("jdbc:mysql://localhost:3306/blog");
dataSource.setUser("root");
dataSource.setPassword("zhangting");
qryRun = new QueryRunner(dataSource);
dbmb = getDatabaseMetaData();
}
private java.sql.DatabaseMetaData getDatabaseMetaData() {
Properties info = new Properties();
info.setProperty("user", "root");
info.setProperty("password", "zhangting");
java.sql.DatabaseMetaData metaData = null;
try {
metaData = new JDBC4Connection("localhost", 3306, info, "blog", null).getMetaData();
} catch (SQLException e) {
e.printStackTrace();
}
return metaData;
}
@Override
public <T extends Object> List<T> findAll(Class<T> clazz) {
ResultSetHandler<List<T>> rsh = new BeanListHandler<T>(clazz);
List<T> result = null;
try {
result = qryRun.query("select * from " + clazz.getSimpleName(), rsh);
logger.debug("SQL: select * from " + clazz.getSimpleName());
} catch (SQLException e) {
logger.error("Can not this query table " + clazz.getSimpleName(), e);
}
return result;
}
@Override
public <T> T findById(Class<T> clazz, int id) {
ResultSetHandler<T> rsh = new BeanHandler<T>(clazz);
T result = null;
try {
ResultSet rs = dbmb.getPrimaryKeys(null, null, clazz.getSimpleName());
String primary_key = null;
while (rs.next()) {
primary_key = rs.getString("Column_name");
}
if (!"".equals(primary_key) || null != primary_key) {
result = qryRun.query("select * from " + clazz.getSimpleName() +
" where " + primary_key + "=?", rsh, new Object[] { id });
logger.debug("SQL: select * from " + clazz.getSimpleName() + " where " +

primary_key + "=" + id);
} else {
logger.error("This table " + clazz.getSimpleName() + " has not primary key");
throw new SQLException("This table has not primary key");
}
} catch (SQLException e) {
logger.error("Can not this query table " + clazz.getSimpleName(), e);
}
return result;
}
@Override
public List<Map<String, Object>> executeQuery(String sql, Object... args) {
MapListHandler rsh = new MapListHandler();
List<Map<String, Object>> result = null;
try {
result = qryRun.query(sql, rsh, args);
} catch (SQLException e) {
e.printStackTrace();
}
return result;
}
@Override
public long insert(String sql, Object... args) {
return executeUpdate(sql, args);
}
@Override
public long update(String sql, Object... args) {
return executeUpdate(sql, args);
}
@Override
public void delete(String sql, Object... args) {
executeUpdate(sql, args);
}
@Override
public long executeUpdate(String sql, Object... args) {
long id = 0;
try {
id = qryRun.update(sql, args);
} catch (SQLException e) {
logger.error("This table can not changed !", e);
}
return id;
}
@Override
public int[] batchUpdate(String sql, Object[][] objs) {
int[] ids = null;
try {
ids = qryRun.batch(sql, objs);
} catch (SQLException e) {
e.printStackTrace();
}
return ids;
}
}

看见这个QueryRunner了吗，这个类就是我们应该控制的类。然后对数据库的一步步工作都由这个东西来帮我们完成了。

是不是突然觉得真的很简单？简简单单的一个调用就把一切工作都帮我们完成了，其实我们使用到的无非就是query、update、batch操作。

操作完成的结果都是由实现ResultSetHandler此接口的类来完成的。看一下我们都可以将结果包装成什么类型来返回给客户端吧。



看一下吧，都是我们常用到的容器类。实现一些常用的结果返回已经足够了。再来看一下它的core包。



BasicRowProcessor与BeanRowProcessor主要是将数据库的记录封装到各个容器与bean文件中。DbUtils主要就是完成了以前ResultSet，Connection，statement这些个的关闭啊，回滚啊。一些个我们以前写个简单查询就要噼里啪啦写一大堆的东西。现在没那么麻烦了，因为DbUtils已经帮我们完成了。

接下来再写个测试类来测试一下是否通过吧。

package org.byent.dao.impl.test;
import java.util.List;
import java.util.Map;
import junit.framework.Assert;
import org.byent.dao.Dao;
import org.byent.dao.impl.DaoImpl;
import org.byent.pojo.Sex;
import org.junit.Before;
import org.junit.Test;
public class DaoImplTest {
private Dao dao;
@Before
public void testDaoImpl() {
dao = new DaoImpl();
}
@Test
public void testFindAll() {
List<Sex> result = dao.findAll(Sex.class);
Assert.assertEquals(result.size(), 6);
}
@Test
public void testFindById() {
Sex sex = dao.findById(Sex.class, 4);
Assert.assertEquals(sex.getSex_mc(), "男");
}
@Test
public void testExecuteQuery() {
List<Map<String, Object>> result = dao.executeQuery("select * from sex where sex_id=?", new Object[] { 1 });
Assert.assertEquals(result.get(0).get("sexId"), "女");
}
@Test
public void testInsert() {
long id = dao.insert("insert into sex (sex_mc) values (?)", new Object[] { "男" });
Assert.assertNotNull(id);
}
@Test
public void testUpdate() {
long id = dao.update("update sex set sex_mc=? where sex_id=?", new Object[] { "男", 5 });
Assert.assertEquals(id, 5);
}
@Test
public void testDelete() {
dao.delete("delete from sex where sex_id=?", new Object[] { 5 });
}
// @Test
public void testExecuteUpdate() {
}
@Test
public void testBatchUpdate() {
Object[][] objs = new Object[][] { { "man" }, { "women" }, { "man" } };
int[] ids = dao.batchUpdate("insert into sex (sex_mc) values(?)", objs);
Assert.assertEquals(3, ids.length);
}

}