javaweb
一.学习内容
1，DBUtils 工具
（1）QueryRunner 类
（2）ResultSetHandler 接口
（3）BeaHandler 实现类
BeaListHandler
2.编写代码如下：
（1）
package cn.itcat.chapter10.example;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import javax.sql.DataSource;
import org.apache.commons.dbcp.BasicDataSource;
public class excample01 {
public static DataSource ds=null;
static {
BasicDataSource bds=new BasicDataSource();
bds.setDriverClassName("com.mysql.cj.jdbc.Driver");
bds.setUrl("jdbc:mysql://localhost:3306/jdbc?serverTimezone=Asia/Shanghai");
bds.setUsername("root");
bds.setPassword("123456");
bds.setInitialSize(5);
bds.setMaxActive(10);
ds=bds;
}
public static void main(String[] args) throws Exception {
Connection conn=ds.getConnection();
DatabaseMetaData metaData=conn.getMetaData();
System.out.println(metaData.getURL());
System.out.println(metaData.getUserName());
System.out.println(metaData.getDriverVersion());
}
}
（2）
package cn.itcat.chapter10.example;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.SQLException;
import java.util.Properties;
import javax.sql.DataSource;
import org.apache.commons.dbcp.BasicDataSource;
import org.apache.commons.dbcp.BasicDataSourceFactory;
public class excample02 {
public static DataSource ds=null;
static {
Properties prop= new Properties();
try {
InputStream in =new excample02().getClass().getClassLoader().getResourceAsStream("dbcp.properties");
prop.load(in);
ds=BasicDataSourceFactory.createDataSource(prop);
}catch(Exception e){
e.printStackTrace();
}
}
public static void main(String[] args) throws SQLException {
Connection conn=ds.getConnection();
DatabaseMetaData metaData=conn.getMetaData();
System.out.println(metaData.getURL());
System.out.println(metaData.getUserName());
System.out.println(metaData.getDriverVersion());
System.out.println(metaData.getDriverName());
}
}
（3）
package cn.itcat.chapter10.example;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.SQLException;
import javax.sql.DataSource;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class excample03 {
public static DataSource ds=null;
static {
ComboPooledDataSource cpds=new ComboPooledDataSource();
try {
cpds.setDriverClass("com.mysql.cj.jdbc.Driver");
cpds.setJdbcUrl("jdbc:mysql://localhost:3306/jdbc?serverTimezone=Asia/Shanghai");
cpds.setUser("root");
cpds.setPassword("123456");
cpds.setInitialPoolSize(5);
cpds.setMaxPoolSize(10);
ds=cpds;
}catch(Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) throws SQLException {
Connection conn=ds.getConnection();
DatabaseMetaData metaData=conn.getMetaData();
System.out.println(metaData.getURL());
System.out.println(metaData.getUserName());
System.out.println(metaData.getDriverVersion());
System.out.println(metaData.getDriverName());
}
}
（4）
package cn.itcat.chapter10.example;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.SQLException;
import javax.sql.DataSource;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class excample034 {
public static DataSource ds=null;
static {
ComboPooledDataSource cpds=new ComboPooledDataSource("itcast");
ds=cpds;
}
public static void main(String[] args) throws SQLException {
System.out.println(ds.getConnection());
}
}
（5）
package cn.itcat.chapter10.example;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import org.apache.commons.dbutils.ResultSetHandler;
public class BaseDao {
public static Object query(String sql,ResultSetHandler<?> rsh,Object...params) {
Connection conn=null;
PreparedStatement pstmt=null;
ResultSet rs =null;
try {
conn=JDBCUtils.getConnection();
pstmt=conn.prepareStatement(sql);
for(int i=0;params!=null && i<params.length;i++)
{
pstmt.setObject(i+1, params[i]);
}
rs=pstmt.executeQuery();
Object obj=rsh.handle(rs);
return obj;
}catch(Exception e) {
e.printStackTrace();
}
finally {
JDBCUtils.release(rs, pstmt, conn);
}
return rs;
}
}
（6）
该类用来封装user对象
package cn.itcat.chapter10.example;
public class User {
private int id;
private String name;
private String password;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
（7）
该类用于演示BeanHandler类结果集的处理
package cn.itcat.chapter10.example;
import java.sql.SQLException;
import org.apache.commons.dbutils.handlers.BeanHandler;
public class ResultSetTest {
public static void testBeanHandler() throws SQLException {
BaseDao basebao= new BaseDao();
String sql="select * from user where id=?";
Object object= basebao.query(sql, new BeanHandler(User.class),1);
if(object!=null && object instanceof User) {
User user =(User) object;
System.out.println("id 为1的User对象的name值为：" +user.getName());
}else {
System.out.println("查询结果为空:" +object);
}
}
public static void main(String[] args) throws SQLException {
testBeanHandler();
}
}
（8）
该类用于演示BeanListHandler类对结果集的处理
package cn.itcat.chapter10.example;
import java.sql.SQLException;
import java.util.ArrayList;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.BeanHandler;
public class ResultSetTest2 {
public static void testBeanHandler() throws SQLException {
BaseDao basedao= new BaseDao();
String sql="select * from user where id=?";
ArrayList<User> list=(ArrayList<User>) basedao.query(sql, new BeanListHandler(User.class));
for(int i = 0; i < list.size();i++) {
System.out.println("id 为" + i+"的用户名：" +list.get(i).getName());
}
}
public static void main(String[] args) throws SQLException {
testBeanHandler();
}
}
效果图
