合并和拆分map，合并和拆分list,应用于把表格的两行并排显示

最新推荐文章于 2024-10-25 11:56:34 发布

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最新推荐文章于 2024-10-25 11:56:34 发布

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本文链接：https://blog.youkuaiyun.com/qq_23145857/article/details/51601249

本文介绍了如何合并和拆分Map以及List，特别地，展示了如何将表格数据按行合并显示。通过Java代码示例，演示了如何利用`putAll()`方法合并两个Map，并在遇到相同Key时使用后面的值覆盖前面的值。同时，展示了如何拆分JSON数据并将其分为两个List，最后将这两个List合并成一个新的List，以便在一排中并排显示两个数据。此外，还给出了在JSP页面中显示这些数据的示例代码。

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合并两个map:

eg1.

public static void main(String args[])
{
   Map<String, Object> map =new HashMap<String, Object>();
   Map<String, Object> map1 =new HashMap<String, Object>();

   map.put("1",new Integer(1));
   map.put("2", new Integer(2));
   map1.put("3", new Integer(3));
   map1.put("4", new Integer(4));
   map.putAll(map1);
   System.out.println(map1);

   System.out.println(map);
}

结果是：

{3=3, 4=4}

{3=3, 2=2, 1=1, 4=4}

eg2

HashMap map=new HashMap();
map.put("1", "A");
HashMap map1 = new HashMap();
map1.put("2", "B");
map1.put("3", "C");
map.putAll(map1);
System.out.println(map);

打印结果：
{3=C, 2=B, 1=A}
如果是如下：
HashMap map=new HashMap();
map.put("1", "A");
HashMap map1 = new HashMap();
map1.put("2", "B");
map1.put("1", "C");
map.putAll(map1);
System.out.println(map);
打印结果：
{2=B, 1=C}

所以说用putAll就可以合并两个MAP，只不过如果有相同的key那么用后面的覆盖前面的

像下面水位这样的表，循环一排显示两个数据的：原理还是一排显示一个数据，”只不过这个数据里有两个数据“

controller里：

//全部测站点实时数据
@RequestMapping(value = "thereal")
public ModelAndView thereal(
@RequestParam(value = "stcd", required = false, defaultValue = "") String stcd,
@RequestParam(value = "pageIndex", required = false, defaultValue = "0") Integer pageIndex,
@RequestParam(value = "pageSize", required = false, defaultValue = "10") Integer pageSize,
HttpServletRequest request, HttpServletResponse response) throws IOException {

String urlwater="http://192.168.1.15:8080/pingshan-service/data/Query1?sttp=ZZ";
String datawater=result(urlwater);
int indexdaowater=datawater.indexOf("{");
String resultdaowater=datawater.substring(indexdaowater);
String resultdaowater2=resultdaowater.replace(")","");
// 得到一个json对象
JSONObject jsObjwater = JSONObject.fromObject(resultdaowater2);

JSONArray jsonArraywater = jsObjwater.getJSONArray("data");
List<Map<String, Object>> listwater =new ArrayList();

List<Map<String, Object>> listwater1 =new ArrayList();
List<Map<String, Object>> listwater2 =new ArrayList();
List<Map<String, Object>> listwaters =new ArrayList();
//拆分json并把它分为两个list
for(int i=0;i<jsonArraywater.size();i++){
JSONObject jobj = (JSONObject) jsonArraywater.get(i);
Map mapwater3 = new HashMap();
if(i%2==0){//把奇数个归为一类
Map mapwater11 = new HashMap();
String stcd1 = (String) jobj.get("stcd");
String tm1 = (String) jobj.get("tm");
Double z1 = (Double) jobj.get("z");
String stnm1 = (String) jobj.get("stnm");
mapwater11.put("stcd1", stcd1);
mapwater11.put("tm1", tm1);
mapwater11.put("z1", z1);
mapwater11.put("stnm1", stnm1);

listwater1.add(mapwater11);
}else {//把偶数个归为一类
Map mapwater21 = new HashMap();
String stcd2 = (String) jobj.get("stcd");System.out.println(i+"stcd2:"+stcd2);
String tm2 = (String) jobj.get("tm");
Double z2 = (Double) jobj.get("z");
String stnm2 = (String) jobj.get("stnm");
mapwater21.put("stcd2", stcd2);
mapwater21.put("tm2", tm2);
mapwater21.put("z2", z2);
mapwater21.put("stnm2", stnm2);

listwater2.add(mapwater21);
}
}
//判断奇偶，把两个list通过map合并为一个list
if (jsonArraywater.size() % 2 == 0) {//为偶数时
for (int j = 0; j < jsonArraywater.size() / 2; j++) {
Map mapwater = new HashMap();
mapwater.put("stcd1", listwater1.get(j).get("stcd1"));
mapwater.put("tm1", listwater1.get(j).get("tm1"));
mapwater.put("z1", listwater1.get(j).get("z1"));
mapwater.put("stnm1", listwater1.get(j).get("stnm1"));

mapwater.put("stcd2", listwater2.get(j).get("stcd2"));
mapwater.put("tm2", listwater2.get(j).get("tm2"));
mapwater.put("z2", listwater2.get(j).get("z2"));
mapwater.put("stnm2", listwater2.get(j).get("stnm2"));

listwater.add(mapwater);
}

} else {
for (int j = 0; j < (jsonArraywater.size() + 1) / 2; j++) {

if (j < (jsonArraywater.size() - 1) / 2) {//为奇数全部有数据时
Map mapwater = new HashMap();
mapwater.put("stcd1", listwater1.get(j).get("stcd1"));
mapwater.put("tm1", listwater1.get(j).get("tm1"));
mapwater.put("z1", listwater1.get(j).get("z1"));
mapwater.put("stnm1", listwater1.get(j).get("stnm1"));
mapwater.put("stcd2", listwater2.get(j).get("stcd2"));
mapwater.put("tm2", listwater2.get(j).get("tm2"));
mapwater.put("z2", listwater2.get(j).get("z2"));
mapwater.put("stnm2", listwater2.get(j).get("stnm2"));
listwater.add(mapwater);
} else {//最后一对，一个有数据，一个没数据
Map mapwater = new HashMap();
mapwater.put("stcd1", "");
mapwater.put("tm1", "");
mapwater.put("z1", "");
mapwater.put("stnm1", "");
mapwater.put("stcd2",listwater2.get(j).get("stcd2"));
mapwater.put("tm2", listwater2.get(j).get("tm2"));
mapwater.put("z2", listwater2.get(j).get("z2"));
mapwater.put("stnm2",listwater2.get(j).get("stnm2"));
listwater.add(mapwater);
}

}
}

JSONObject jsonwater= new JSONObject();
jsonwater.put("data", listwater);
JSONArray jsonArraywaters = jsonwater.getJSONArray("data");//得到list的形式

String urlrain="http://192.168.1.15:8080/pingshan-service/data/Query1?sttp=PP";
String datarain=result(urlrain);
int indexdaorain=datarain.indexOf("{");
String resultdaorain=datarain.substring(indexdaorain);
String resultdaorain2=resultdaorain.replace(")","");System.out.println("resultdaorain2"+resultdaorain2);
// 得到一个json对象
JSONObject jsObjrain = JSONObject.fromObject(resultdaorain2);
JSONArray jsonArrayrain = jsObjrain.getJSONArray("data");

String urlneilao="http://192.168.1.15:8080/pingshan-service/data/Query1?sttp=NL";
String dataneilao=result(urlneilao);
int indexdaoneilao=dataneilao.indexOf("{");
String resultdaoneilao=dataneilao.substring(indexdaoneilao);
String resultdaoneilao2=resultdaoneilao.replace(")","");
// 得到一个json对象
JSONObject jsObjneilao = JSONObject.fromObject(resultdaoneilao2);
JSONArray jsonArrayneilao = jsObjneilao.getJSONArray("data");

HashMap queryParams = new HashMap();

queryParams.put("water", jsonArraywaters);
queryParams.put("rain", jsonArrayrain);
queryParams.put("neilao", jsonArrayneilao);

return new ModelAndView("thereals", queryParams);

}

//根据接口地址获取数据
public String result(String urls) {
String url = urls;
// 地址对象
URL webUrl = null;
try {
webUrl = new URL(url);
} catch (MalformedURLException e) {

e.printStackTrace();
}
// 建立远程连接
HttpURLConnection conn = null;
try {
conn = (HttpURLConnection) webUrl.openConnection();
} catch (IOException e) {

e.printStackTrace();
}
// 得到输入流
InputStream ins = null;
try {
ins = conn.getInputStream();
} catch (IOException e) {

e.printStackTrace();
}

// 字符读取流
BufferedReader bfr = null;
try {
bfr = new BufferedReader(new InputStreamReader(ins,
"UTF-8"));
} catch (UnsupportedEncodingException e) {

e.printStackTrace();
}
// 使用字符串构造器，将读取的每一行数据拼接起来
StringBuffer sb = new StringBuffer();

String content = null;
try {
while ((content = bfr.readLine()) != null) {
sb.append(content);
}
} catch (IOException e) {

e.printStackTrace();
}
// 关闭字符流
try {
bfr.close();
} catch (IOException e) {

e.printStackTrace();
}
// 释放连接
conn.disconnect();
// 得到返回的字符串
String data = sb.toString();
return data;
}

jsp页面上：

<td style="width:">
<label><span style="color:#4884CE;">测站名称</span></label>
</td>
<td style="width:">
<label><span style="color:#4884CE;">时间</span></label>
</td>
<td style="width:">
<label><span style="color:#4884CE;">水位(m)</span></label>
</td>
</tr>

<c:forEach items="${water}" var="item" varStatus="s">
<tr>
<td>${item.stnm1}(${item.stcd1})</td><td>${item.tm1}</td><td>${item.z1}</td>//第一排第一列
<td>${item.stnm2}(${item.stcd2})</td><td>${item.tm2}</td><td>${item.z2}</td>//第一排第二列
</tr>
</c:forEach>

</table>

</div>
部分重要代码：

String urlwater="http://192.168.1.15:8080/pingshan-service/data/Query1?sttp=ZZ";
String datawater=result(urlwater);
int indexdaowater=datawater.indexOf("{");
String resultdaowater=datawater.substring(indexdaowater);
String resultdaowater2=resultdaowater.replace(")","");
// 得到一个json对象
JSONObject jsObjwater = JSONObject.fromObject(resultdaowater2);

JSONArray jsonArraywater = jsObjwater.getJSONArray("data");
List<Map<String, Object>> listwater =new ArrayList();

List<Map<String, Object>> listwater1 =new ArrayList();
List<Map<String, Object>> listwater2 =new ArrayList();
List<Map<String, Object>> listwaters =new ArrayList();
//拆分json并把它分为两个list
for(int i=0;i<jsonArraywater.size();i++){
   JSONObject jobj = (JSONObject) jsonArraywater.get(i);
   Map mapwater3 = new HashMap();
if(i%2==0){//把奇数个归为一类
  Map mapwater11 = new HashMap();
   String stcd1 = (String) jobj.get("stcd");
   String tm1 = (String) jobj.get("tm");
   Double z1 = (Double) jobj.get("z");
   String stnm1 = (String) jobj.get("stnm");
   mapwater11.put("stcd1", stcd1);
   mapwater11.put("tm1", tm1);
   mapwater11.put("z1", z1);
   mapwater11.put("stnm1", stnm1);

     listwater1.add(mapwater11);
}else {//把偶数个归为一类
Map mapwater21 = new HashMap();
  String stcd2 = (String) jobj.get("stcd");System.out.println(i+"stcd2:"+stcd2);
   String tm2 = (String) jobj.get("tm");
   Double z2 = (Double) jobj.get("z");
   String stnm2 = (String) jobj.get("stnm");
   mapwater21.put("stcd2", stcd2);
   mapwater21.put("tm2", tm2);
   mapwater21.put("z2", z2);
   mapwater21.put("stnm2", stnm2);

     listwater2.add(mapwater21);
}
}
//判断奇偶，把两个list通过map合并为一个list
if (jsonArraywater.size() % 2 == 0) {//为偶数时
for (int j = 0; j < jsonArraywater.size() / 2; j++) {
Map mapwater = new HashMap();
mapwater.put("stcd1", listwater1.get(j).get("stcd1"));
mapwater.put("tm1", listwater1.get(j).get("tm1"));
mapwater.put("z1", listwater1.get(j).get("z1"));
mapwater.put("stnm1", listwater1.get(j).get("stnm1"));

mapwater.put("stcd2", listwater2.get(j).get("stcd2"));
mapwater.put("tm2", listwater2.get(j).get("tm2"));
mapwater.put("z2", listwater2.get(j).get("z2"));
mapwater.put("stnm2", listwater2.get(j).get("stnm2"));

listwater.add(mapwater);
}

} else {
for (int j = 0; j < (jsonArraywater.size() + 1) / 2; j++) {

if (j < (jsonArraywater.size() - 1) / 2) {//为奇数全部有数据时
Map mapwater = new HashMap();
mapwater.put("stcd1", listwater1.get(j).get("stcd1"));
mapwater.put("tm1", listwater1.get(j).get("tm1"));
mapwater.put("z1", listwater1.get(j).get("z1"));
mapwater.put("stnm1", listwater1.get(j).get("stnm1"));
mapwater.put("stcd2", listwater2.get(j).get("stcd2"));
mapwater.put("tm2", listwater2.get(j).get("tm2"));
mapwater.put("z2", listwater2.get(j).get("z2"));
mapwater.put("stnm2", listwater2.get(j).get("stnm2"));
listwater.add(mapwater);
} else {//最后一对，一个有数据，一个没数据
Map mapwater = new HashMap();
mapwater.put("stcd1", "");
mapwater.put("tm1", "");
mapwater.put("z1", "");
mapwater.put("stnm1", "");
mapwater.put("stcd2",listwater2.get(j).get("stcd2"));
mapwater.put("tm2", listwater2.get(j).get("tm2"));
mapwater.put("z2", listwater2.get(j).get("z2"));
mapwater.put("stnm2",listwater2.get(j).get("stnm2"));
listwater.add(mapwater);
}

}
}

JSONObject   jsonwater = new JSONObject();
jsonwater.put("data", listwater);
JSONArray   jsonArraywaters = jsonwater.getJSONArray("data");//得到list的形式