Java URL编码与解码基础详解

String originalUrl = "https://example.com/search?q=Java编码测试&page=1";
String encodedUrl = URLEncoder.encode(originalUrl, StandardCharsets.UTF_8);
System.out.println("编码后：" + encodedUrl);

String encodedUrl = "https%3A%2F%2Fexample.com%2Fsearch%3Fq%3DJava%E7%BC%96%E7%A0%81%E6%B5%8B%E8%AF%95%26page%3D1";
String decodedUrl = URLDecoder.decode(encodedUrl, StandardCharsets.UTF_8);
System.out.println("解码后：" + decodedUrl);

String baseUrl = "https://example.com/path with space/";
String query = "name=张三&age=25";

String encodedPath = URLEncoder.encode(baseUrl, StandardCharsets.UTF_8)
    .replace("%3A", ":")
    .replace("%2F", "/");
String encodedQuery = URLEncoder.encode(query, StandardCharsets.UTF_8);

String fullUrl = encodedPath + "?" + encodedQuery;
System.out.println("完整编码URL：" + fullUrl);

Map<String, String> params = new HashMap<>();
params.put("key1", "value&with/special=chars");
params.put("key2", "another value");

String queryString = params.entrySet().stream()
    .map(entry -> entry.getKey() + "=" + 
         URLEncoder.encode(entry.getValue(), StandardCharsets.UTF_8))
    .collect(Collectors.joining("&"));

System.out.println("参数编码结果：" + queryString);

try {
    URI uri = new URI("https", "example.com", "/path with space/", "param=值", null);
    String encodedUri = uri.toASCIIString();
    System.out.println("URI编码结果：" + encodedUri);
    
    URI decodedUri = new URI(encodedUri);
    System.out.println("URI解码路径：" + decodedUri.getPath());
} catch (URISyntaxException e) {
    e.printStackTrace();
}

String url = UriComponentsBuilder.fromHttpUrl("https://example.com/api")
    .path("/search")
    .queryParam("query", "Java 编码")
    .queryParam("page", 2)
    .build()
    .encode(StandardCharsets.UTF_8)
    .toUriString();

System.out.println("Spring构建的URL：" + url);

String doubleEncoded = URLEncoder.encode(URLEncoder.encode("测试", "UTF-8"), "UTF-8");
System.out.println("双重编码结果：" + doubleEncoded);

String singleDecoded = URLDecoder.decode(doubleEncoded, "UTF-8");
System.out.println("单次解码：" + singleDecoded);
System.out.println("完全解码：" + URLDecoder.decode(singleDecoded, "UTF-8"));

String gb2312Encoded = URLEncoder.encode("中文", "GB2312");
System.out.println("GB2312编码：" + gb2312Encoded);

try {
    String utf8Decoded = URLDecoder.decode(gb2312Encoded, "UTF-8");
    System.out.println("用UTF-8解码GB2312编码结果：" + utf8Decoded);
} catch (Exception e) {
    System.out.println("编码不匹配导致解码失败");
}

// 重用编码器实例
CharsetEncoder encoder = StandardCharsets.UTF_8.newEncoder();
CharsetDecoder decoder = StandardCharsets.UTF_8.newDecoder();

// 批量处理示例
List<String> urls = Arrays.asList("url1", "url2", "url3");
List<String> encodedUrls = urls.stream()
    .map(url -> {
        try {
            return URLEncoder.encode(url, StandardCharsets.UTF_8);
        } catch (Exception e) {
            return url;
        }
    })
    .collect(Collectors.toList());