resultMap的元素是在iBATIS的最重要和最強(qiáng)大的元素。您可以通過(guò)使用iBATIS的結(jié)果映射減少高達(dá)90%的JDBC編碼,在某些情況下,可以讓你做JDBC不支持的事情。
ResultMaps的設(shè)計(jì)是這樣的簡(jiǎn)單語(yǔ)句不需要明確的結(jié)果映射,以及更復(fù)雜的報(bào)表要求不超過(guò)絕對(duì)必要說(shuō)明的關(guān)系。
本章將只給你一個(gè)簡(jiǎn)單的介紹iBATIS的結(jié)果映射。
我們已經(jīng)在MySQL下有EMPLOYEE表:
CREATE TABLE EMPLOYEE ( id INT NOT NULL auto_increment, first_name VARCHAR(20) default NULL, last_name VARCHAR(20) default NULL, salary INT default NULL, PRIMARY KEY (id) );
此表有如下兩條記錄:
mysql> select * from EMPLOYEE; +----+------------+-----------+--------+ | id | first_name | last_name | salary | +----+------------+-----------+--------+ | 1 | Zara | Ali | 5000 | | 2 | Roma | Ali | 3000 | +----+------------+-----------+--------+ 2 row in set (0.00 sec)
使用iBATIS的結(jié)果映射,需要修改Employee.java文件。因此,讓我們保持它,因?yàn)樗呀?jīng)在前一章中使用過(guò)。
public class Employee { private int id; private String first_name; private String last_name; private int salary; /* Define constructors for the Employee class. */ public Employee() {} public Employee(String fname, String lname, int salary) { this.first_name = fname; this.last_name = lname; this.salary = salary; } /* Here are the required method definitions */ public int getId() { return id; } public void setId(int id) { this.id = id; } public String getFirstName() { return first_name; } public void setFirstName(String fname) { this.first_name = fname; } public String getLastName() { return last_name; } public void setlastName(String lname) { this.last_name = lname; } public int getSalary() { return salary; } public void setSalary(int salary) { this.salary = salary; } } /* End of Employee */
在這里,我們將修改Employee.xml文件介紹<resultMap></ resultMap>標(biāo)記。這個(gè)標(biāo)簽就必須在我們<select>標(biāo)記的resultMap屬性運(yùn)行此結(jié)果映射這是需要一個(gè)id。
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE sqlMap PUBLIC "-//ibatis.apache.org//DTD SQL Map 2.0//EN" "http://ibatis.apache.org/dtd/sql-map-2.dtd"> <sqlMap namespace="Employee"> <!-- Perform Insert Operation --> <insert id="insert" parameterClass="Employee"> INSERT INTO EMPLOYEE(first_name, last_name, salary) values (#first_name#, #last_name#, #salary#) <selectKey resultClass="int" keyProperty="id"> select last_insert_id() as id </selectKey> </insert> <!-- Perform Read Operation --> <select id="getAll" resultClass="Employee"> SELECT * FROM EMPLOYEE </select> <!-- Perform Update Operation --> <update id="update" parameterClass="Employee"> UPDATE E