基于Spring MVC的Web应用开发(8) - Convert
UsherOu 2013-02-25
本文介绍SpringMVC中的Convert，Convert是我认为的SpringMVC最吸引人，最优雅的特性，下面通过例子程序领略一下：
package org.springframework.samples.mvc.convert;
import java.util.Collection;
import java.util.Date;
import org.springframework.format.annotation.DateTimeFormat;
import org.springframework.format.annotation.DateTimeFormat.ISO;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
@Controller
@RequestMapping("/convert/*")
public class ConvertController {
@RequestMapping("primitive")
public @ResponseBody String primitive(@RequestParam Integer value) {
return "Converted primitive " + value;
}
// requires Joda-Time on the classpath
@RequestMapping("date/{value}")
public @ResponseBody String date(@PathVariable @DateTimeFormat(iso=ISO.DATE) Date value) {
return "Converted date " + value;
}
@RequestMapping("collection")
public @ResponseBody String collection(@RequestParam Collection<Integer> values) {
return "Converted collection " + values;
}
@RequestMapping("formattedCollection")
public @ResponseBody String formattedCollection(@RequestParam @DateTimeFormat(iso=ISO.DATE) Collection<Date> values) {
return "Converted formatted collection " + values;
}
@RequestMapping("bean")
public @ResponseBody String bean(JavaBean bean) {
return "Converted " + bean;
}
@RequestMapping("value")
public @ResponseBody String valueObject(@RequestParam SocialSecurityNumber value) {
return "Converted value object " + value;
}
@RequestMapping("custom")
public @ResponseBody String customConverter(@RequestParam @MaskFormat("###-##-####") String value) {
return "Converted '" + value + "' with a custom converter";
}
} package org.springframework.samples.mvc.convert;
import java.util.Collection;
import java.util.Date;
import org.springframework.format.annotation.DateTimeFormat;
import org.springframework.format.annotation.DateTimeFormat.ISO;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
@Controller
@RequestMapping("/convert/*")
public class ConvertController {
@RequestMapping("primitive")
public @ResponseBody String primitive(@RequestParam Integer value) {
return "Converted primitive " + value;
}
// requires Joda-Time on the classpath
@RequestMapping("date/{value}")
public @ResponseBody String date(@PathVariable @DateTimeFormat(iso=ISO.DATE) Date value) {
return "Converted date " + value;
}
@RequestMapping("collection")
public @ResponseBody String collection(@RequestParam Collection<Integer> values) {
return "Converted collection " + values;
}
@RequestMapping("formattedCollection")
public @ResponseBody String formattedCollection(@RequestParam @DateTimeFormat(iso=ISO.DATE) Collection<Date> values) {
return "Converted formatted collection " + values;
}
@RequestMapping("bean")
public @ResponseBody String bean(JavaBean bean) {
return "Converted " + bean;
}
@RequestMapping("value")
public @ResponseBody String valueObject(@RequestParam SocialSecurityNumber value) {
return "Converted value object " + value;
}
@RequestMapping("custom")
public @ResponseBody String customConverter(@RequestParam @MaskFormat("###-##-####") String value) {
return "Converted '" + value + "' with a custom converter";
}
}逐一方法看过来：
1.
@RequestMapping("primitive")
public @ResponseBody String primitive(@RequestParam Integer value) {
return "Converted primitive " + value;
} @RequestMapping("primitive")
public @ResponseBody String primitive(@RequestParam Integer value) {
return "Converted primitive " + value;
}@RequestParam自动获取URL提交的参数名为value的值并赋值到Integer value变量，
访问"http://localhost:8080/web/convert/primitive?value=1"
浏览器显示"Converted primitive 1"
2.
// requires Joda-Time on the classpath
@RequestMapping("date/{value}")
public @ResponseBody String date(@PathVariable @DateTimeFormat(iso=ISO.DATE) Date value) {
return "Converted date " + value;
} // requires Joda-Time on the classpath
@RequestMapping("date/{value}")
public @ResponseBody String date(@PathVariable @DateTimeFormat(iso=ISO.DATE) Date value) {
return "Converted date " + value;
}@PathVariable自动获取URL路径中date/后面的值，判断该值是否满足ISO.DATE的类型（yyyy-MM-dd），最后将这个字符串转成Date value，
访问"http://localhost:8080/web/convert/date/2012-03-30"
浏览器显示"Converted date Fri Mar 30 00:00:00 CST 2012"
3.
@RequestMapping("collection")
public @ResponseBody String collection(@RequestParam Collection<Integer> values) {
return "Converted collection " + values;
} @RequestMapping("collection")
public @ResponseBody String collection(@RequestParam Collection<Integer> values) {
return "Converted collection " + values;
}如果提交了同名参数的多个值（例如html的多选框），这些值会自动的封装到Collection<Integer> values里，
访问"http://localhost:8080/web/convert/collection?values=1&values=2"
浏览器显示"Converted collection [1, 2]"
4.
@RequestMapping("formattedCollection")
public @ResponseBody String formattedCollection(@RequestParam @DateTimeFormat(iso=ISO.DATE) Collection<Date> values) {
return "Converted formatted collection " + values;
} @RequestMapping("formattedCollection")
public @ResponseBody String formattedCollection(@RequestParam @DateTimeFormat(iso=ISO.DATE) Collection<Date> values) {
return "Converted formatted collection " + values;
}访问"http://localhost:8080/web/convert/formattedCollection?values=2012-03-30&values=2012-12-25"
浏览器显示"Converted formatted collection [Fri Mar 30 00:00:00 CST 2012, Tue Dec 25 00:00:00 CST 2012]"
以上说的都是convert简单类型，下面讲解如何convert自定义的Java类，写一个JavaBean类，该类有几个属性：
private Integer primitive;
@DateTimeFormat(iso=ISO.DATE)
private Date date;
@MaskFormat("(###) ###-####")
private String masked;
// list will auto-grow as its dereferenced e.g. list[0]=value
private List<Integer> list;
// annotation type conversion rule will be applied to each list element
@DateTimeFormat(iso=ISO.DATE)
private List<Date> formattedList;
// map will auto-grow as its dereferenced e.g. map[key]=value
private Map<Integer, String> map;
// nested will be set when it is referenced e.g. nested.foo=value
private NestedBean nested; private Integer primitive;
@DateTimeFormat(iso=ISO.DATE)
private Date date;
@MaskFormat("(###) ###-####")
private String masked;
// list will auto-grow as its dereferenced e.g. list[0]=value
private List<Integer> list;
// annotation type conversion rule will be applied to each list element
@DateTimeFormat(iso=ISO.DATE)
private List<Date> formattedList;
// map will auto-grow as its dereferenced e.g. map[key]=value
private Map<Integer, String> map;
// nested will be set when it is referenced e.g. nested.foo=value
private NestedBean nested;注意到该JavaBean还嵌套了一个自定义的Java类NestedBean，该类的属性为：
private String foo; private List<NestedBean> list; private Map<String, NestedBean> map;
private String foo; private List<NestedBean> list; private Map<String, NestedBean> map;
看一下详细用法：
5.
访问"http://localhost:8080/web/convert/bean?primitive=1"
浏览器显示"Converted JavaBean primitive=1"
6.
访问"http://localhost:8080/web/convert/bean?date=2012-03-30"
浏览器显示"Converted JavaBean date=Fri Mar 30 00:00:00 CST 2012"
7.
访问"http://localhost:8080/web/convert/bean?masked=(123)-456-7890"
浏览器显示"Converted JavaBean masked=(123) 456-7890"
8.
访问"http://localhost:8080/web/convert/bean?list[0]=1&list[1]=2"
浏览器显示"Converted JavaBean list=[1, 2]"
9.
访问"http://localhost:8080/web/convert/bean?formattedList[0]=2012-03-30&formattedList[1]=2012-12-25"
浏览器显示"Converted JavaBean formattedList=[Fri Mar 30 00:00:00 CST 2012, Tue Dec 25 00:00:00 CST 2012]"
10.
访问"http://localhost:8080/web/convert/bean?map[1]=a&map[2]=b"
浏览器显示"Converted JavaBean map={1=a, 2=b}"
11.
访问"http://localhost:8080/web/convert/bean?nested.foo=stephansun"
浏览器显示"Converted JavaBean nested=NestedBean foo=stephansun"
12.
访问"http://localhost:8080/web/convert/bean?nested.list[0].foo=stephansun"
浏览器显示"Converted JavaBean nested=NestedBean list=[NestedBean foo=stephansun]"
13.
访问"http://localhost:8080/web/convert/bean?nested.map[1].foo=stephansun"
浏览器显示"Converted JavaBean nested=NestedBean map={1=NestedBean foo=stephansun}"
14.
访问"http://localhost:8080/web/convert/value?value=1"
浏览器显示"Converted value object SocialSecurityNumber [value=1]"
15.
访问"http://localhost:8080/web/convert/custom?value=ab-cd-efgh"
浏览器显示"Converted 'ab-cd-efgh' with a custom converter"
