前言

• 关于URI参考这里。
• springboot 2.1.1.RELEASE

UriComponentsBuilder

• UriComponentsBuilder 是UriBuilder的实现。针对Servlet，还派生出来ServletUriComponentsBuilder。
• 使用过UriComponentsBuilder 的都知道，很好用

快速来个示例

String url = UriComponentsBuilder.fromUriString("http://mydomain/api/getToken").queryParam("appid", "123").queryParam("appsecret", "secret123").build().encode().toString(); System.out.println(url);

• 这段代码可以得到：http://mydomain/api/getToken?appid=123&appsecret=secret123
• 这段代码实际做了几件事：
• 实例化 UriComponentsBuilder 。UriComponentsBuilder.fromUriString("http://mydomain/api/getToken")
• 设置 UriComponentsBuilder 实例。.queryParam("appid", "123").queryParam("appsecret", "secret123")
• 创建 UriComponents 实例。.build()
• 设置 UriComponents 实例。.encode()
• UriComponents 实例转成字符串。.toString()

实例化 UriComponentsBuilder 的方法

UriComponentsBuilder 提供的实例化 UriComponentsBuilder 的方法

public static UriComponentsBuilder newInstance(); public static UriComponentsBuilder fromPath(String path); public static UriComponentsBuilder fromUri(URI uri); public static UriComponentsBuilder fromUriString(String uri); public static UriComponentsBuilder fromHttpUrl(String httpUrl); public static UriComponentsBuilder fromHttpRequest(HttpRequest request); public static UriComponentsBuilder fromOriginHeader(String origin);

ServletUriComponentsBuilder 提供的实例化 UriComponentsBuilder 的方法

public static ServletUriComponentsBuilder fromContextPath(HttpServletRequest); public static ServletUriComponentsBuilder fromServletMapping(HttpServletRequest); public static ServletUriComponentsBuilder fromRequest(HttpServletRequest); public static ServletUriComponentsBuilder fromCurrentContextPath(); public static ServletUriComponentsBuilder fromCurrentServletMapping(); public static ServletUriComponentsBuilder fromCurrentRequest();

设置 UriComponentsBuilder 实例

赋值

.queryParam("appid", "123")

重复赋值

.queryParam("appid", "123") .queryParam("appid", "234")

• appid 会变为[“123”, “234”]

替换

.queryParam("appid", "123") .replaceQueryParam("appid", "234")

• appid 变为234

路径

.path("a") .path("b") .path("c")

• xxx/a/b/c

替换路径

.path("a") .path("b") .path("c") .replacePath("d")

• xxx/d

更多

略。

关于urlencode

前面示例中.build() 中得到的是 UriComponents 派生类（HierarchicalUriComponents）的实例。

HierarchicalUriComponents 类的实例在.encode()时，使用HierarchicalUriComponents.encodeUriComponent() 方法进行 url 编码。其编码方式与java.net.URLEncoder的实现不同。

总结一下（代码参考测试代码1）：

代码结果特征遵循协议

URLEncoder.encode(“1 + 2 = 3”, “utf-8”);	1+%2B+2+%3D+3	空格转义成+；+转义成%2B	W3C标准规定
HierarchicalUriComponents.encodeUriComponent(“1 + 2 = 3”, “utf-8”,Type.QUERY_PARAM);	1%20+%202%20%3D%203	空格转义成%20；+不变	RFC 3986

用哪个对呢？都对！！！但，要看提供服务的应用支持哪个。我的建议是，都试试，哪个能用用哪个。

如何让 URLEncoder 支持 空格转义成%20；+不变呢？

参考这里：https://blog.csdn.net/qq_43566496/article/details/84935364

如何让 HierarchicalUriComponents 支持 空格转义成+；+转义成%2B呢？

方法1

String url = UriComponentsBuilder.fromUriString("http://mydomain/api/getToken").queryParam("appid", "123").queryParam("appsecret", "secret123").queryParam("q", URLEncoder.encode("1 + 2 = 3")).build(true).encode().toString(); System.out.println(url);

• .build(true) 告诉 UriComponents 我已经做过uri编码了，你就不要再做uri编码了。

方法2

String url = UriComponentsBuilder.fromUriString("http://mydomain/api/getToken").queryParam("appid", "123").queryParam("appsecret", "secret123").queryParam("q", URLEncoder.encode("1 + 2 = 3")).build().toString(); System.out.println(url);

• 去掉.encode() ， UriComponents 就不要再做uri编码了。

spring 提供的支持 RFC 2396、RFC 3986 的类： UriUtils

https://docs.spring.io/spring-framework/docs/3.0.x/javadoc-api/org/springframework/web/util/UriUtils.html

测试代码1

import java.io.ByteArrayOutputStream; import java.io.UnsupportedEncodingException; import java.net.URLEncoder; import java.nio.charset.Charset;import org.springframework.util.Assert; import org.springframework.util.StreamUtils; import org.springframework.util.StringUtils;public class Test {public static void main(String[] args) throws UnsupportedEncodingException {System.out.println(URLEncoder.encode("1 + 2 = 3", "utf-8"));System.out.println(encodeUriComponent("1 + 2 = 3", Charset.forName("utf-8"), Type.QUERY_PARAM));}/*HierarchicalUriComponents.encodeUriComponent() 方法的高仿实现*/static String encodeUriComponent(String source, Charset charset, Type type) {if (!StringUtils.hasLength(source)) {return source;}Assert.notNull(charset, "Charset must not be null");Assert.notNull(type, "Type must not be null");byte[] bytes = source.getBytes(charset);boolean original = true;for (byte b : bytes) {if (!type.isAllowed(b)) {original = false;break;}}if (original) {return source;}ByteArrayOutputStream baos = new ByteArrayOutputStream(bytes.length);for (byte b : bytes) {if (type.isAllowed(b)) {baos.write(b);}else {baos.write('%');char hex1 = Character.toUpperCase(Character.forDigit((b >> 4) & 0xF, 16));char hex2 = Character.toUpperCase(Character.forDigit(b & 0xF, 16));baos.write(hex1);baos.write(hex2);}}return StreamUtils.copyToString(baos, charset);}enum Type {QUERY {@Overridepublic boolean isAllowed(int c) {return isPchar(c) || '/' == c || '?' == c;}},QUERY_PARAM {@Overridepublic boolean isAllowed(int c) {if ('=' == c || '&' == c) {return false;}else {return isPchar(c) || '/' == c || '?' == c;}}};/*** Indicates whether the given character is allowed in this URI component.* @return {@code true} if the character is allowed; {@code false} otherwise*/public abstract boolean isAllowed(int c);/*** Indicates whether the given character is in the {@code ALPHA} set.* @see <a href="http://www.ietf.org/rfc/rfc3986.txt">RFC 3986, appendix A</a>*/protected boolean isAlpha(int c) {return (c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z');}/*** Indicates whether the given character is in the {@code DIGIT} set.* @see <a href="http://www.ietf.org/rfc/rfc3986.txt">RFC 3986, appendix A</a>*/protected boolean isDigit(int c) {return (c >= '0' && c <= '9');}/*** Indicates whether the given character is in the {@code sub-delims} set.* @see <a href="http://www.ietf.org/rfc/rfc3986.txt">RFC 3986, appendix A</a>*/protected boolean isSubDelimiter(int c) {return ('!' == c || '$' == c || '&' == c || '\'' == c || '(' == c || ')' == c || '*' == c || '+' == c ||',' == c || ';' == c || '=' == c);}/*** Indicates whether the given character is in the {@code unreserved} set.* @see <a href="http://www.ietf.org/rfc/rfc3986.txt">RFC 3986, appendix A</a>*/protected boolean isUnreserved(int c) {return (isAlpha(c) || isDigit(c) || '-' == c || '.' == c || '_' == c || '~' == c);}/*** Indicates whether the given character is in the {@code pchar} set.* @see <a href="http://www.ietf.org/rfc/rfc3986.txt">RFC 3986, appendix A</a>*/protected boolean isPchar(int c) {return (isUnreserved(c) || isSubDelimiter(c) || ':' == c || '@' == c);}} } String url = UriComponentsBuilder.fromUriString("http://api.fanyi.baidu.com/api/trans/vip/translate").queryParam("appid", appid).queryParam("q", encode(query)).queryParam("from", from).queryParam("to", to).queryParam("salt", salt).queryParam("sign", sign).build(true).encode().toString();

参考

https://www.cnblogs.com/zhengxl5566/p/10783422.html
https://www.cnblogs.com/zhengxl5566/p/13492602.html
https://www.cnblogs.com/siqi/p/10070926.html

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