java中拼接兩個對象集合

目標:  根據兩個list中每條記錄的某個屬性是否相同來拼接。

1.首先定義一個字符串

String str = "[{\"ITEMID\":2,\"ITEMNAME\":\"人大常委辦公廳\",\"BILLTYPEID\":1,\"BILLTYPENAME\":\"一般繳款書\"},\n" +
        " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委辦公廳\",\"BILLTYPEID\":3,\"BILLTYPENAME\":\"退付書（微機）\"},\n" +
        " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委辦公廳\",\"BILLTYPEID\":41,\"BILLTYPENAME\":\"高速公路收費專用票據（500元）\"},\n" +
        " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委辦公廳\",\"BILLTYPEID\":720,\"BILLTYPENAME\":\"單位手寫繳款書（本局）\"},\n" +
        " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委辦公廳\",\"BILLTYPEID\":721,\"BILLTYPENAME\":\"單位微機繳款書（本局）\"},\n" +
        " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委辦公廳\",\"BILLTYPEID\":743,\"BILLTYPENAME\":\"收入專用收據（機打）\"}\n" +
        "]";
2.然后將str先轉換成json格式，然后再轉換成list1： 代碼如下

ObjectMapper mapper = new ObjectMapper();
List<Map<String,Object>> conList = null;
   conList = mapper.readValue(str, List.class);

3.ObjectMapper的使用需要導入jar包或者在pom文件中添加依賴：

<dependency>
   <groupId>org.codehaus.jackson</groupId>
   <artifactId>jackson-mapper-asl</artifactId>
   <version>1.7.1</version>
</dependency>
4.通過mybatis查詢表中的數據，用list接收

List<EInvoiceThresholdDTO> list = new ArrayList<EInvoiceThresholdDTO>();
list = eInoviceThresholdMapper.selectAll();

5.然后通過循環嵌套，對比出BILLTYPEID，如果相同則將表中查出的部分屬性通過list的put方法添加到list conList中
上完整代碼：

@Override
public List<Map<String,Object>> selectAll() {
    String str = "[{\"ITEMID\":2,\"ITEMNAME\":\"人大常委辦公廳\",\"BILLTYPEID\":1,\"BILLTYPENAME\":\"一般繳款書\"},\n" +
            " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委辦公廳\",\"BILLTYPEID\":3,\"BILLTYPENAME\":\"退付書（微機）\"},\n" +
            " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委辦公廳\",\"BILLTYPEID\":41,\"BILLTYPENAME\":\"高速公路收費專用票據（500元）\"},\n" +
            " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委辦公廳\",\"BILLTYPEID\":720,\"BILLTYPENAME\":\"單位手寫繳款書（本局）\"},\n" +
            " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委辦公廳\",\"BILLTYPEID\":721,\"BILLTYPENAME\":\"單位微機繳款書（本局）\"},\n" +
            " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委辦公廳\",\"BILLTYPEID\":743,\"BILLTYPENAME\":\"收入專用收據（機打）\"}\n" +
            "]";
    List<EInvoiceThresholdDTO> list = new ArrayList<EInvoiceThresholdDTO>();
    list = eInoviceThresholdMapper.selectAll();
    ObjectMapper mapper = new ObjectMapper();
    List<Map<String,Object>> conList = null;
    try {
        conList = mapper.readValue(str, List.class);
        for (int i=0;i<conList.size();i++){
            for (int j=0;j<list.size();j++){
                if (conList.get(i).get("BILLTYPEID").toString().equals(list.get(j).getBillTypeID().toString())){
                    conList.get(i).put("AGENCY",list.get(j).getAGENCY());
                    conList.get(i).put("YEAR",list.get(j).getYEAR());
                    conList.get(i).put("WRITEUSER",list.get(j).getWRITEUSER());
                    conList.get(i).put("WRITEDATE",list.get(j).getWRITEDATE());
                    conList.get(i).put("ISENABLE",list.get(j).getISENABLE());
                    conList.get(i).put("ISAUTO",list.get(j).getISAUTO());
                    conList.get(i).put("threshold",list.get(j).getThreshold());
                }
            }
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
    return conList;
}