Spring MVC 知識彙總

普通的mvc配置
在web.xml中

<servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <!-- 
        DispatcherServlet在執行初始化方法時，
        會啓動spring容器，所以，需要指定spring
        配置文件的位置。
     -->

    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:applicationContext.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
    <servlet-name>springmvc</servlet-name>
    <url-pattern>*.do</url-pattern>
</servlet-mapping>

請求 到首先先匹配 url-pattern，如果匹配成功，則 再 到servlet-mapping中的servlet-name。
再到servlet中的servlet-name，最後到servlet-class

Spring+Jdbc
簡單配置
1.在配置文件中填寫配置信息

maxactive=1
maxwait=5000

classname=oracle.jdbc.driver.OracleDriver
url=jdbc:oracle:thin:@localhost:1521:xe
username=jsd1607
password=1234

2在resources/applicationContext.xml中 讀取配置信息

<util:properties id="config" 
    location="classpath:config.properties"/>
    <!-- 配置DataSource -->
    <bean id="ds" class="org.apache.commons.dbcp.BasicDataSource"
    destroy-method="close">
    <property name="driverClassName" value="#{config.classname}" />
    <property name="url" value="#{config.url}" />
    <property name="username" value="#{config.username}" />
    <property name="password" value="#{config.password}" />
</bean>  

3.配置JdbcTemplate

<bean id="jt" class="org.springframework.jdbc.core.JdbcTemplate">
    <property name="dataSource" ref="ds" />
</bean>

4.設置組件掃描

<bean id="jt" class="org.springframework.jdbc.core.JdbcTemplate">
    <property name="dataSource" ref="ds" />
</bean>

5，寫相對應的實體類

package entity;

public class Emp {
    private Integer id;
    private String ename;
    private Integer age;
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getEname() {
        return ename;
    }
    public void setEname(String ename) {
        this.ename = ename;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    @Override
    public String toString() {
        return "Emp [id=" + id + ", ename=" + ename + ", age=" + age + "]";
    }

}

6.實現JDBC

package dao;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

import javax.annotation.Resource;

import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.stereotype.Repository;

import entity.Emp;

@Repository("empDAO")
public class EmpDAO {
    @Resource(name="jt")
    private JdbcTemplate jt;

/**
 * spring jdbc 將底層的jdbc異常
 * 捕獲之後，統一轉換成了一些運行時
 * 異常(RuntimeException)，然後拋出。
 */
public void save(Emp emp){
    String sql = "INSERT INTO emp "
            + "VALUES(emp_seq.nextval,?,?)";
    Object[] args = 
            new Object[]{emp.getEname(),
                    emp.getAge()};
    jt.update(sql, args);
}

public List<Emp> findAll(){
    String sql = "SELECT * FROM emp";
    return jt.query(sql, new EmpRowMapper());
}

/*
 * queryForObject方法：如果找不到
 * 對應的記錄，會拋出異常。
 */
public Emp findById(int id){
    String sql = "SELECT * FROM emp "
            + "WHERE id = ?";
    Object[] args = 
            new Object[]{id};
    return jt.queryForObject(
            sql,args, new EmpRowMapper());
}

public Emp findById2(int id){
    String sql = "SELECT * FROM emp "
            + "WHERE id = ?";
    Object[] args = 
            new Object[]{id};
    List<Emp> emps = 
            jt.query(sql, args,
                    new EmpRowMapper());
    if(emps != null && emps.size() > 0){
        return emps.get(0);
    }
    return null;
}

public void modify(Emp emp){
    String sql = "UPDATE emp "
            + "SET ename=?,age=? "
            + "WHERE id=?";
    Object[] args = 
            new Object[]{emp.getEname(),
                    emp.getAge(),
                    emp.getId()};
    jt.update(sql, args);
}

public void delete(int id){
    String sql = "DELETE FROM emp "
            + "WHERE id=?";
    Object[] args = 
            new Object[]{id};
    jt.update(sql, args);
}


/*
 * RowMapper類封裝瞭如何將記錄
 * 轉換成相應的實體對象。
 */
class EmpRowMapper 
    implements RowMapper<Emp>{
    //index:正在被遍歷的記錄的下標。
    public Emp mapRow(
            ResultSet rs, int index) 
                    throws SQLException {
        Emp emp = new Emp();
        emp.setId(rs.getInt("id"));
        emp.setEname(rs.getString("ename"));
        emp.setAge(rs.getInt("age"));
        return emp;
    }

}

}

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