2018-05-23

第三章 springmvc注解式开发

3.1 第一个程序

3.1.1 注解

springmvc.xml

<!-- 组件扫描器 -->
<context:component-scan base-package="com.bjpowernode.handlers"></context:component-scan>

控制器

@org.springframework.stereotype.Controller
public class MyController {
    @RequestMapping("/my.do")
    public ModelAndView doSome(HttpServletRequest arg0, HttpServletResponse arg1) {
        return new ModelAndView("/WEB-INF/jsp/welcome.jsp");
    }

}

3.1.2 多个请求指向同一个处理器、一个处理器中定义多个处理器方法

@org.springframework.stereotype.Controller
public class MyController {
    @RequestMapping({"/first.do","hello.do"})
    public ModelAndView doFirst(HttpServletRequest arg0, HttpServletResponse arg1) {
        return new ModelAndView("/WEB-INF/jsp/welcome.jsp");
    }

    @RequestMapping("/second.do")
    public ModelAndView doSecond(HttpServletRequest arg0, HttpServletResponse arg1) {
        return new ModelAndView("/WEB-INF/jsp/welcome.jsp");
    }
}

3.1.3 命名空间 @RequestMapping

@org.springframework.stereotype.Controller
@RequestMapping("xxx/ooo/jjj")
public class MyController {
    @RequestMapping({"/first.do","hello.do"})
    public ModelAndView doFirst(HttpServletRequest arg0, HttpServletResponse arg1) {
        return new ModelAndView("/WEB-INF/jsp/welcome.jsp");
    }

    @RequestMapping("/second.do")
    public ModelAndView doSecond(HttpServletRequest arg0, HttpServletResponse arg1) {
        return new ModelAndView("/WEB-INF/jsp/welcome.jsp");
    }
}

3.1.4 请求中的通配符

@RequestMapping("/second*.do")

3.1.5 对请求提交方式的定义

@RequestMapping(value={"/first.do","hello.do"}, method= RequestMethod.POST)

3.2 处理器方法的参数

处理器方法常用的参数有五类，这些参数会在系统调用时由系统自动赋值，即程序员可以在方法内直接使用。

HttpServleRequest
HttpServletResponse
HttpSession
用于承载数据的Model
请求中所携带的参数

3.3 处理器方法接收请求里的参数

index.jsp

<form action="${pageContext.request.contextPath }/test/register.do" method="POST">
    姓名：<input type="text" name="name" /><br />
    年龄：<input type="text" name="age" /><br />
    <input type="submit" value="注册" />
</form>

welcome.jsp

name=${name}
age=${age }

web.xml

添加过滤器，解决中文乱码问题

<filter>
      <filter-name>CharacterEncodingFilter</filter-name>
      <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
      <init-param>
          <param-name>encoding</param-name>
          <param-value>utf-8</param-value>
      </init-param>
      <init-param>
          <param-name>forceEncoding</param-name>
          <param-value>true</param-value>
      </init-param>
</filter>

<filter-mapping>
    <filter-name>CharacterEncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

3.3.1 接收请求参数 - 逐个接收

控制器

@org.springframework.stereotype.Controller
@RequestMapping("/test")
public class MyController {
    @RequestMapping(value={"/register.do"}, method= RequestMethod.POST)
    public ModelAndView doRegister(String name, int age) {
        System.out.println("name="+name);
        System.out.println("age="+age);

        ModelAndView mv = new ModelAndView();
        mv.addObject("name", name);
        mv.addObject("age", age);
        mv.setViewName("/WEB-INF/jsp/welcome.jsp");
        return mv;
    }

}

3.3.2 接收请求参数 - 校正请求参数名

参数pname

姓名：<input type="text" name="pname" /><br />

@RequestParam校正

public ModelAndView doRegister(@RequestParam("pname") String name, int age) {...}

3.3.3 接收请求参数 - 以对象形式整体接收

Student.class

public class Student {
    private String name;
    private int age;

    ...
    getter and setter
    ...

}

控制器

@org.springframework.stereotype.Controller
@RequestMapping("/test")
public class MyController {
    @RequestMapping(value={"/register.do"}, method= RequestMethod.POST)
    public ModelAndView doRegister(Student student) {
        System.out.println("name="+student.getName());
        System.out.println("age="+student.getAge());

        ModelAndView mv = new ModelAndView();
        mv.addObject("name", student);
        mv.setViewName("/WEB-INF/jsp/welcome.jsp");
        return mv;
    }

}

整体接收，要求参数名name,age要与实体类属性名相同

3.3.3 接收请求参数 - 域属性参数的接收

Student.class

public class Student {
    private String name;
    private int age;
    private School school;
    ...
        getter and setter
    ...
}

School.class

public class School {
    private String sname;
    private String address;
    public String getSname() {
        return sname;
    }
    ...
        getter and setter
    ...        
}

index.jsp

<form action="${pageContext.request.contextPath }/test/register.do" method="POST">
    姓名：<input type="text" name="name" /><br />
    年龄：<input type="text" name="age" /><br />
    学校：<input type="text" name="School.sname" /><br />
    校址：<input type="text" name="School.address" /><br />
    <input type="submit" value="注册" />
</form>

3.4 处理器方法的返回值

3.4.1 返回ModelAndView

当处理器方法处理完后，既需要跳转到其它资源，也需要在资源间传递数据，那么就应该使用ModelAndView。

@org.springframework.stereotype.Controller
@RequestMapping("/test")
public class MyController {
    @RequestMapping(value={"/register.do"}, method= RequestMethod.POST)
    public ModelAndView doRegister(Student student) {
        ModelAndView mv = new ModelAndView();
        mv.addObject("name", student);
        mv.setViewName("/WEB-INF/jsp/welcome.jsp");
        return mv;
    }

}

3.4.2 返回String

只需要进行跳转，而不需要进行数据传递时，可以使用String。

@org.springframework.stereotype.Controller
@RequestMapping("/test")
public class MyController {
    @RequestMapping(value={"/register.do"}, method= RequestMethod.POST)
    public String soSome() {
        return "/WEB-INF/jsp/welcome.jsp";
    }

}

物理视图：/WEB-INF/jsp/welcome.jsp

逻辑视图：welcome，需要视图解析器转换为物理视图

3.4.3 返回void

index.jsp

<script type="text/javascript">
    $(function (){
        $("button").click(function(){
            $.ajax({
                url:"test/ajax.do",
                data:{
                    name:"zhangsan",
                    age:23
                },
                success:function(data){
                    var json=eval("("+ data +")");
                    alert(json.name + json.age);
                }
            });
        });
    });
</script>
<button>ajax submit</button>

处理器

@org.springframework.stereotype.Controller
@RequestMapping("/test")
public class MyController {
    @RequestMapping("/ajax.do")
    public void doAjax(String name, int age, HttpServletResponse response) throws IOException {
        HashMap<String, Object> map = new HashMap<String, Object>();
        map.put("name", name);
        map.put("age", age);

        JSONObject json = JSONObject.fromObject(map);
        String jsonStr = json.toString();

        PrintWriter out = response.getWriter();
        out.println(jsonStr);
    }

}

需要导入json-lib相关的包

3.4.4 返回Object

处理器方法也可以返回Object对象，但返回的这个Object对象不是作为逻辑视图出现的，而是作为直接在页面显示的数据出现的。

返回Object对象，需要使用@ResponseBody注解，将转换后的JSON数据放入到响应体中。

#####（1）、环境搭建

A、导入jar包

由于返回Object数据，一般都是将数据转化为了JSON对象后传递给浏览器页面的。而这个由Object转换为JSON，是由Jackson工具完成的。所以需要导入Jackson的相关jar包。

jackson-annotations、jackson-core、jackson-databind

B、注册注解驱动

将Object数据转化为JSON数据，需要由http消息转换器HttpMessageConvert完成。而消息转换器的开启，需要由<mvc:annotation-driven>来完成。

当Spring容器进行初始化过程中在<mvc:annotation-driven>处创建注解驱动时，默认创建了七个HttpMessageConvert对象。也就是说，我们注册<mvc:annotation-driven>，就是为了让容器为我们创建HttpMessageConvert对象。

C、@ResponseBody

给处理器方法添加注解

（2）、返回Object-数值型

springmvc.xml

<?xml version="1.0" encoding="utf-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <!-- 注册组件扫描器 -->
    <context:component-scan base-package="com.bjpowernode.handlers"></context:component-scan>

    <!-- 注册注解驱动器 -->
    <mvc:annotation-driven></mvc:annotation-driven>

</beans>

处理器

@org.springframework.stereotype.Controller
@RequestMapping("/test")
public class MyController {

    @RequestMapping("/ajax.do")
    @ResponseBody //将要返回的数据放入到响应体中
    public Object doAjax() {
        return 123.321;
    }

}

index.jsp

<script type="text/javascript">
    $(function (){
        $("button").click(function(){
            $.ajax({
                url:"test/ajax.do",
                success:function(data){
                    alert(data);
                }
            });
        });
    });
</script>
 <button>ajax submit</button>

（3）、返回Object-字符串

@org.springframework.stereotype.Controller
@RequestMapping("/test")
public class MyController {

    @RequestMapping(value="/ajax.do",produces="text/html;charset=utf-8")
    @ResponseBody //将要返回的数据放入到响应体中
    public Object doAjax() {
        return "临沂";
    }

}

produces指定返回的字符串格式

（4）、返回Object-自定义对象

处理器

@org.springframework.stereotype.Controller
@RequestMapping("/test")
public class MyController {

    @RequestMapping("/ajax.do")
    @ResponseBody //将要返回的数据放入到响应体中
    public Object doAjax() {
        return new Student("zhangsan",23);
    }

}

index.jsp

<script type="text/javascript">
    $(function (){
        $("button").click(function(){
            $.ajax({
                url:"test/ajax.do",
                success:function(data){
                    alert(data.name + data.age);
                }
            });
        });
    });
</script>
<button>ajax submit</button>

（4）、返回Object-List集合

处理器

@org.springframework.stereotype.Controller
@RequestMapping("/test")
public class MyController {

    @RequestMapping("/ajax.do")
    @ResponseBody //将要返回的数据放入到响应体中
    public Object doAjax() {
        ArrayList<Student> list = new ArrayList<Student>();
        list.add(new Student("zhangsan",23));
        list.add(new Student("lisi",23));
        return list;
    }

}

index.jsp

<script type="text/javascript">
    $(function (){
        $("button").click(function(){
            $.ajax({
                url:"test/ajax.do",
                success:function(data){
                    $(data).each(function(index){
                        alert(data[index].name + data[index].age);
                    });
                }
            });
        });
    });
</script>
 <button>ajax submit</button>

（5）、返回Object-Map集合

处理器

@org.springframework.stereotype.Controller
@RequestMapping("/test")
public class MyController {

    @RequestMapping("/ajax.do")
    @ResponseBody //将要返回的数据放入到响应体中
    public Object doAjax() {
        HashMap<String, Student> map = new HashMap<String,Student>();
        map.put("stu1", new Student("zhangsan",23));
        map.put("stu2", new Student("lisi",24));
        return map;
    }

}

index.jsp

<script type="text/javascript">
    $(function (){
        $("button").click(function(){
            $.ajax({
                url:"test/ajax.do",
                success:function(data){
                    $(data).each(function(index){
                        alert(data.stu1.name + data.stu2.age);
                    });
                }
            });
        });
    });
</script>
<button>ajax submit</button>