Spring入门详细教程（四）

前言

本篇紧接着spring入门详细教程（三），建议阅读本篇前，先阅读第一篇，第二篇以及第三篇。链接如下：

Spring入门详细教程（一） https://www.cnblogs.com/jichi/p/10165538.html

Spring入门详细教程（二） https://www.cnblogs.com/jichi/p/10176601.html

Spring入门详细教程（三） https://www.cnblogs.com/jichi/p/10177004.html

本篇主要讲解spring的jdbcTemplate相关。

一、spring整合jdbc继承jdbcdaosupport的方式

1、导入所需jar包。

除了之前介绍的spring的基础包，还需要导入数据库连接池包，jdbc驱动包，spring的jdbc包，spring的事务。

2、书写dao层代码。

public class UserDaoImpl extends JdbcDaoSupport implements UserDao {
    @Override
    public void save(User u) {
        String sql = "insert into user values('1',?) ";
        super.getJdbcTemplate().update(sql, u.getName());
    }
    @Override
    public void delete(Integer id) {
        String sql = "delete from user where id = ? ";
        super.getJdbcTemplate().update(sql,id);
    }
    @Override
    public void update(User u) {
        String sql = "update  user set name = ? where id=? ";
        super.getJdbcTemplate().update(sql, u.getName(),u.getId());
    }
    @Override
    public User getById(Integer id) {
        String sql = "select * from user where id = ? ";
        return super.getJdbcTemplate().queryForObject(sql,new RowMapper<User>(){
            @Override
            public User mapRow(ResultSet rs, int arg1) throws SQLException {
                User u = new User();
                u.setId(rs.getInt("id"));
                u.setName(rs.getString("name"));
                return u;
            }}, id);
        
    }
    @Override
    public int getTotalCount() {
        String sql = "select count(*) from user  ";
        Integer count = super.getJdbcTemplate().queryForObject(sql, Integer.class);
        return count;
    }
    @Override
    public List<User> getAll() {
        String sql = "select * from user  ";
        List<User> list = super.getJdbcTemplate().query(sql, new RowMapper<User>(){
            @Override
            public User mapRow(ResultSet rs, int arg1) throws SQLException {
                User u = new User();
                u.setId(rs.getInt("id"));
                u.setName(rs.getString("name"));
                return u;
            }});
        return list;
    }
}

3、建立数据库链接配置文件

jdbc.jdbcUrl=jdbc:mysql:///spring
jdbc.driverClass=com.mysql.jdbc.Driver
jdbc.user=root
jdbc.password=1234

4、在spring容器中进行配置

<!-- 指定spring读取db.properties配置 -->
<context:property-placeholder location="classpath:db.properties"  />
<!-- 将连接池放入spring容器 -->
<bean name="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" >
    <property name="jdbcUrl" value="${jdbc.jdbcUrl}" ></property>
    <property name="driverClass" value="${jdbc.driverClass}" ></property>
    <property name="user" value="${jdbc.user}" ></property>
    <property name="password" value="${jdbc.password}" ></property>
</bean>
<!-- 将UserDao放入spring容器 -->
<bean name="userDao" class="com.jichi.jdbctemplate.UserDaoImpl" >
    <property name="dataSource" ref="dataSource" ></property>
</bean>

5、由于userDaoImpl已经继承了jdbcDaoSupport。jdbcDaoSupport中已经定义了jdbcTemplate，同时内置了setDataSource。可以自动将连接池放入。源码如下：

/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.jdbc.core.support;

import java.sql.Connection;
import javax.sql.DataSource;

import org.springframework.dao.support.DaoSupport;
import org.springframework.jdbc.CannotGetJdbcConnectionException;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.datasource.DataSourceUtils;
import org.springframework.jdbc.support.SQLExceptionTranslator;

/**
 * Convenient super class for JDBC-based data access objects.
 *
 * <p>Requires a {@link javax.sql.DataSource} to be set, providing a
 * {@link org.springframework.jdbc.core.JdbcTemplate} based on it to
 * subclasses through the {@link #getJdbcTemplate()} method.
 *
 * <p>This base class is mainly intended for JdbcTemplate usage but can
 * also be used when working with a Connection directly or when using
 * {@code org.springframework.jdbc.object} operation objects.
 *
 * @author Juergen Hoeller
 * @since 28.07.2003
 * @see #setDataSource
 * @see #getJdbcTemplate
 * @see org.springframework.jdbc.core.JdbcTemplate
 */
public abstract class JdbcDaoSupport extends DaoSupport {

    private JdbcTemplate jdbcTemplate;


    /**
     * Set the JDBC DataSource to be used by this DAO.
     */
    public final void setDataSource(DataSource dataSource) {
        if (this.jdbcTemplate == null || dataSource != this.jdbcTemplate.getDataSource()) {
            this.jdbcTemplate = createJdbcTemplate(dataSource);
            initTemplateConfig();
        }
    }

    /**
     * Create a JdbcTemplate for the given DataSource.
     * Only invoked if populating the DAO with a DataSource reference!
     * <p>Can be overridden in subclasses to provide a JdbcTemplate instance
     * with different configuration, or a custom JdbcTemplate subclass.
     * @param dataSource the JDBC DataSource to create a JdbcTemplate for
     * @return the new JdbcTemplate instance
     * @see #setDataSource
     */
    protected JdbcTemplate createJdbcTemplate(DataSource dataSource) {
        return new JdbcTemplate(dataSource);
    }

    /**
     * Return the JDBC DataSource used by this DAO.
     */
    public final DataSource getDataSource() {
        return (this.jdbcTemplate != null ? this.jdbcTemplate.getDataSource() : null);
    }

    /**
     * Set the JdbcTemplate for this DAO explicitly,
     * as an alternative to specifying a DataSource.
     */
    public final void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
        initTemplateConfig();
    }

    /**
     * Return the JdbcTemplate for this DAO,
     * pre-initialized with the DataSource or set explicitly.
     */
    public final JdbcTemplate getJdbcTemplate() {
      return this.jdbcTemplate;
    }

    /**
     * Initialize the template-based configuration of this DAO.
     * Called after a new JdbcTemplate has been set, either directly
     * or through a DataSource.
     * <p>This implementation is empty. Subclasses may override this
     * to configure further objects based on the JdbcTemplate.
     * @see #getJdbcTemplate()
     */
    protected void initTemplateConfig() {
    }

    @Override
    protected void checkDaoConfig() {
        if (this.jdbcTemplate == null) {
            throw new IllegalArgumentException("'dataSource' or 'jdbcTemplate' is required");
        }
    }


    /**
     * Return the SQLExceptionTranslator of this DAO's JdbcTemplate,
     * for translating SQLExceptions in custom JDBC access code.
     * @see org.springframework.jdbc.core.JdbcTemplate#getExceptionTranslator()
     */
    protected final SQLExceptionTranslator getExceptionTranslator() {
        return getJdbcTemplate().getExceptionTranslator();
    }

    /**
     * Get a JDBC Connection, either from the current transaction or a new one.
     * @return the JDBC Connection
     * @throws CannotGetJdbcConnectionException if the attempt to get a Connection failed
     * @see org.springframework.jdbc.datasource.DataSourceUtils#getConnection(javax.sql.DataSource)
     */
    protected final Connection getConnection() throws CannotGetJdbcConnectionException {
        return DataSourceUtils.getConnection(getDataSource());
    }

    /**
     * Close the given JDBC Connection, created via this DAO's DataSource,
     * if it isn't bound to the thread.
     * @param con Connection to close
     * @see org.springframework.jdbc.datasource.DataSourceUtils#releaseConnection
     */
    protected final void releaseConnection(Connection con) {
        DataSourceUtils.releaseConnection(con, getDataSource());
    }

}

6、编写测试类

    @Test
    public void fun2() throws Exception{
        User u = new User();
        u.setName("tom");
        ud.save(u);
    }

7、执行成功

二、spring整合jdbctemplate

1、导入所需jar包。

除了之前介绍的spring的基础包，还需要导入数据库连接池包，jdbc驱动包，spring的jdbc包，spring的事务。

2、配置jdbctemplate

<!-- 指定spring读取db.properties配置 -->
<context:property-placeholder location="classpath:db.properties"  />
<!-- 1.将连接池放入spring容器 -->
<bean name="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" >
    <property name="jdbcUrl" value="${jdbc.jdbcUrl}" ></property>
    <property name="driverClass" value="${jdbc.driverClass}" ></property>
    <property name="user" value="${jdbc.user}" ></property>
    <property name="password" value="${jdbc.password}" ></property>
</bean>
<!-- 2.将JDBCTemplate放入spring容器 -->
<bean name="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate" >
    <property name="dataSource" ref="dataSource" ></property>
</bean>
<!-- 3.将UserDao放入spring容器 -->
<bean name="userDao" class="com.jichi.jdbctemplate.UserDaoImpl" >
    <property name="jdbcTemplate" ref="jdbcTemplate" ></property>
</bean>

3、书写dao层代码

public class UserDaoImpl  implements UserDao {
    
    @Resource
    private JdbcTemplate jdbcTemplate;
    
    @Override
    public void save(User u) {
        String sql = "insert into user values('1',?) ";
        jdbcTemplate.update(sql, u.getName());
    }
    @Override
    public void delete(Integer id) {
        String sql = "delete from user where id = ? ";
        jdbcTemplate.update(sql,id);
    }
    @Override
    public void update(User u) {
        String sql = "update  user set name = ? where id=? ";
        jdbcTemplate.update(sql, u.getName(),u.getId());
    }
    @Override
    public User getById(Integer id) {
        String sql = "select * from user where id = ? ";
        return jdbcTemplate.queryForObject(sql,new RowMapper<User>(){
            @Override
            public User mapRow(ResultSet rs, int arg1) throws SQLException {
                User u = new User();
                u.setId(rs.getInt("id"));
                u.setName(rs.getString("name"));
                return u;
            }}, id);
        
    }
    @Override
    public int getTotalCount() {
        String sql = "select count(*) from user  ";
        Integer count = jdbcTemplate.queryForObject(sql, Integer.class);
        return count;
    }
    @Override
    public List<User> getAll() {
        String sql = "select * from user  ";
        List<User> list = jdbcTemplate.query(sql, new RowMapper<User>(){
            @Override
            public User mapRow(ResultSet rs, int arg1) throws SQLException {
                User u = new User();
                u.setId(rs.getInt("id"));
                u.setName(rs.getString("name"));
                return u;
            }});
        return list;
    }
}

4、书写测试方法

    @Test
    public void fun2() throws Exception{
        User u = new User();
        u.setName("tom");
        ud.save(u);
    }

三、spring中jdbctemplate的相关方法

1、update

用来执行insert，update，delete语句。

    @Override
    public void save(User u) {
        String sql = "insert into user values('1',?) ";
        jdbcTemplate.update(sql, u.getName());
    }
    @Override
    public void delete(Integer id) {
        String sql = "delete from user where id = ? ";
        jdbcTemplate.update(sql,id);
    }
    @Override
    public void update(User u) {
        String sql = "update  user set name = ? where id=? ";
        jdbcTemplate.update(sql, u.getName(),u.getId());
    }

2、查询某一具体类

    @Override
    public int getTotalCount() {
        String sql = "select count(*) from user  ";
        Integer count = jdbcTemplate.queryForObject(sql, Integer.class);
        return count;
    }

3、将查询的数据封入实体类（单个对象，实现rowmapper接口）

    @Override
    public User getById(Integer id) {
        String sql = "select * from user where id = ? ";
        return jdbcTemplate.queryForObject(sql,new RowMapper<User>(){
            @Override
            public User mapRow(ResultSet rs, int arg1) throws SQLException {
                User u = new User();
                u.setId(rs.getInt("id"));
                u.setName(rs.getString("name"));
                return u;
            }}, id);
        
    }

4、将查询的数据封入实体类（list对象，实现rowmapper接口）

    @Override
    public List<User> getAll() {
        String sql = "select * from user  ";
        List<User> list = jdbcTemplate.query(sql, new RowMapper<User>(){
            @Override
            public User mapRow(ResultSet rs, int arg1) throws SQLException {
                User u = new User();
                u.setId(rs.getInt("id"));
                u.setName(rs.getString("name"));
                return u;
            }});
        return list;
    }

5、根据数据库查出的字段与实体类字段名自动对应

    @Override
    public List<User> getAll() {
        String sql = "select * from user  ";
        List<User> list = jdbcTemplate.query(sql,new BeanPropertyRowMapper<>(User.class));
        return list;
    }