如何从Hashmap获取键值对的值？ [英] How can I obtain values of key-value pair from a Hashmap?

问题描述

mylogger.info("original request start: "+request.getQueryString());
System.out.println("Query1:" + request.getQueryString());
QueryStats queryStats=new QueryStats();
Map parameterMap = request.getParameterMap()==null? null:new HashMap(request.getParameterMap());
System.out.println("Query2:" + parameterMap);

Collection newParamsValue=parameterMap.values();
Object newParams[]=newParamsValue.toArray();
StringBuffer strParam=new StringBuffer() ;
int l=newParams.length;
for(int i=0;i<l;i++){
    **strParam=strParam.append((StringBuffer)newParams[i]);**
}

我想将所有值都放入字符串中。我怎么才能得到它？

I want to get all the values into a string. How can I get it?

推荐答案

参数图是 Map< String，String []> 。建议的 Object [] #toString（）答案根本不起作用。您还需要遍历 String [] 。此外，您必须对键值对进行URL编码，以便创建正确的HTTP查询字符串。以下是它应该如何完成：

The parameter map is a Map<String, String[]>. The proposed Object[]#toString() answers will not work at all. You need to loop over the String[] as well. Also, you have to URL-encode the key-value pairs in order to create a proper HTTP query string. Here's how it should be done:

public static String toQueryString(Map<String, String[]> params) {
    StringBuilder queryString = new StringBuilder();

    for (Entry<String, String[]> param : params.entrySet()) {
        for (String value : param.getValue()) {
            if (queryString.length() > 0) {
                queryString.append("&amp;");
            }

            queryString
                .append(URLEncoder.encode(param.getKey(), "UTF-8"))
                .append("=")
                .append(URLEncoder.encode(value, "UTF-8"));
        }
    }

    return queryString.toString();
}

使用如下

Map<String, String[]> params = request.getParameterMap();
String queryString = toQueryString(params);
// ...

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