Struts2返回json数据（基于注解配置），并配置json返回需要的json数据

2018-5-8
参考了很多博客，自己亲测可用
导包
struts2-json-plugin-2.1.8.1.jar
json-lib-2.1.jar，

在默认的情况下，不能实现action返回类型为json，此时需要改变默认的继承包，用如下注解@ParentPackage(“json-default”)来改变继承的包为json-default.

@Namespace("/api")
@ParentPackage("json-default")
public class ChannelAPIAction extends BaseAction {

    // private JSONArray json = new JSONArray();
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    @Autowired
    private ProductsService productsService;

    @Action(value = "/findAll", results = { @Result(name = "json", type = "json") })
    public String list() {
        System.out.println("api/list");
        List<Products> list = productsService.list();
        JSONArray json = JSONArray.parseArray(JSON.toJSONString(list));
        JSONObject object = new JSONObject();
        object.put("code", 200);
        object.put("data", json);
        AjaxResponse.ajaxPrintByJson(object);
        return "json";
    }

}

AjaxResponse.ajaxPrintByJson(object);是工具类

    public static void ajaxPrintByJson(Object content) {
        HttpServletResponse response = responseCommon();
        try {   
            response.setContentType("text/json;charset=UTF-8");
            java.io.PrintWriter out = response.getWriter();
            out.print(content);
            out.flush();//这里写的不严谨
            out.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
  public static HttpServletResponse responseCommon(){
        HttpServletResponse response = ServletActionContext.getResponse();
        response.setCharacterEncoding("UTF-8");
        response.setContentType("text/html");
        return response;
    }

结果展示

到这里本来以为大功告成，到后台发现报错 org.apache.commons.lang.xwork.StringUtils
这里有个解决的方案比较好https://blog.csdn.net/qq_27109081/article/details/47127971
思想就是：你少哪个类，我就该你加上。
2018-5-30
修改
以上是把json写入response，这种方式没有必要配置json-default，直接就可以返回json

json-default是可以自动把对象，数组，列表等转化生成json，与springMVC中的@ResponseBody有点像

@ParentPackage("json-default")
public class DemoAction extends BaseAction {

    // private JSONArray json = new JSONArray();
    private List<Products> list = new ArrayList<Products>();

    private Map<String, String> map = new HashMap<String, String>();

    private Products products = new Products();

    @Autowired
    private ProductsService productsService;

    @Action(value = "/api/findAll", results = { @Result(name = "json", type = "json") })
    public String list() {
        System.out.println("api/list");
        list = productsService.list();
        map.put("test1", "value1");
        map.put("key1", "value1");
        products.setCName("cName");
        products.setPrice("123");
        products.setUsername("userName");
        products.setProductName("productName");
        // JSONArray json = JSONArray.parseArray(JSON.toJSONString(list));
        // JSONObject object = new JSONObject();
        // object.put("code", 200);
        // object.put("data", json);
        // AjaxResponse.ajaxPrintByJson(object);
        // AjaxResponse.responseOut(object);
        return "json";
    }

格式不对，直接复制的google浏览器返回的就送数据（json-view插件美化之后）

{
    list: [
        {
            channelName: "asd",
            price: "6301",
            productName: "产品一",
            username: "qds001"
        },
        {
            channelName: "asd",
            price: "6532",
            productName: "产品一",
            username: "qds001"
        }
    ],
    map: {
        test1: "value1",
        key1: "value1"
    },
    products: {
        clName: "cName",
        price: "123",
        productName: "productName",
        username: "userName"
    }
}

上面的返回结果依然不完善，因为返回的是类中所有有getter方法的属性，
需要进一步配置

@Action(value = "/api/findAll", results = { @Result(name = "json", type = "json",params={"root","list"}) })

这种方式返回的是只有list数据

//可以根据自己子想返回的数据自行配置
@Action(value = "/api/findAll", results = { @Result(name = "json", type = "json",params={"includeProperties","list\\[\\d+\\]\\.cName"}) })

返回list列表中cName

@Action(value = "/api/findAll", results = { @Result(name = "json", type = "json",params={"includeProperties","list\\[\\d+\\]\\.channelName,map.*"}) })

返回list特定字段和map
还有一个配置是excludeProperties使用和includeProperties差不多，一个是包含，一个是排除

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以上是基于注解的配置，xml配置请参考官方文档

http://struts.apache.org/plugins/json/

如果返回的json数据格式比较简单，则可以使用这种方式

https://blog.csdn.net/qq_23934475/article/details/80497186