java中拼接两个对象集合

目标:  根据两个list中每条记录的某个属性是否相同来拼接。

1.首先定义一个字符串

String str = "[{\"ITEMID\":2,\"ITEMNAME\":\"人大常委办公厅\",\"BILLTYPEID\":1,\"BILLTYPENAME\":\"一般缴款书\"},\n" +
        " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委办公厅\",\"BILLTYPEID\":3,\"BILLTYPENAME\":\"退付书（微机）\"},\n" +
        " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委办公厅\",\"BILLTYPEID\":41,\"BILLTYPENAME\":\"高速公路收费专用票据（500元）\"},\n" +
        " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委办公厅\",\"BILLTYPEID\":720,\"BILLTYPENAME\":\"单位手写缴款书（本局）\"},\n" +
        " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委办公厅\",\"BILLTYPEID\":721,\"BILLTYPENAME\":\"单位微机缴款书（本局）\"},\n" +
        " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委办公厅\",\"BILLTYPEID\":743,\"BILLTYPENAME\":\"收入专用收据（机打）\"}\n" +
        "]";
2.然后将str先转换成json格式，然后再转换成list1： 代码如下

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

3.ObjectMapper的使用需要导入jar包或者在pom文件中添加依赖：

<dependency>
   <groupId>org.codehaus.jackson</groupId>
   <artifactId>jackson-mapper-asl</artifactId>
   <version>1.7.1</version>
</dependency>
4.通过mybatis查询表中的数据，用list接收

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

5.然后通过循环嵌套，对比出BILLTYPEID，如果相同则将表中查出的部分属性通过list的put方法添加到list conList中
上完整代码：

@Override
public List<Map<String,Object>> selectAll() {
    String str = "[{\"ITEMID\":2,\"ITEMNAME\":\"人大常委办公厅\",\"BILLTYPEID\":1,\"BILLTYPENAME\":\"一般缴款书\"},\n" +
            " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委办公厅\",\"BILLTYPEID\":3,\"BILLTYPENAME\":\"退付书（微机）\"},\n" +
            " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委办公厅\",\"BILLTYPEID\":41,\"BILLTYPENAME\":\"高速公路收费专用票据（500元）\"},\n" +
            " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委办公厅\",\"BILLTYPEID\":720,\"BILLTYPENAME\":\"单位手写缴款书（本局）\"},\n" +
            " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委办公厅\",\"BILLTYPEID\":721,\"BILLTYPENAME\":\"单位微机缴款书（本局）\"},\n" +
            " {\"ITEMID\":2,\"ITEMNAME\":\"人大常委办公厅\",\"BILLTYPEID\":743,\"BILLTYPENAME\":\"收入专用收据（机打）\"}\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;
}