🍃【Spring专题】「技术原理」为大家介绍一下Spring中的Ant路径匹配工具组件AntPathMatcher

Spring中的绝大多数的路径匹配规则是依照Ant的标准来的

实际上不只是SpringMVC，整个Spring框架的路径解析都是按照Ant的风格来的，在Spring中的具体实现,详情参见 org.springframework.util.AntPathMatcher，具体规则如下

/**
 * {@link PathMatcher} implementation for Ant-style path patterns.
 *
 * <p>Part of this mapping code has been kindly borrowed from <a href="http://ant.apache.org">Apache Ant</a>.
 *
 * <p>The mapping matches URLs using the following rules:<br>
 * <ul>
 * <li>{@code ?} matches one character</li>
 * <li>{@code *} matches zero or more characters</li>
 * <li>{@code **} matches zero or more <em>directories</em> in a path</li>
 * <li>{@code {spring:[a-z]+}} matches the regexp {@code [a-z]+} as a path variable named "spring"</li>
 * </ul>
 *
 * <h3>Examples</h3>
 * <ul>
 * <li>{@code com/t?st.jsp} &mdash; matches {@code com/test.jsp} but also
 * {@code com/tast.jsp} or {@code com/txst.jsp}</li>
 * <li>{@code com/*.jsp} &mdash; matches all {@code .jsp} files in the
 * {@code com} directory</li>
 * <li><code>com/&#42;&#42;/test.jsp</code> &mdash; matches all {@code test.jsp}
 * files underneath the {@code com} path</li>
 * <li><code>org/springframework/&#42;&#42;/*.jsp</code> &mdash; matches all
 * {@code .jsp} files underneath the {@code org/springframework} path</li>
 * <li><code>org/&#42;&#42;/servlet/bla.jsp</code> &mdash; matches
 * {@code org/springframework/servlet/bla.jsp} but also
 * {@code org/springframework/testing/servlet/bla.jsp} and {@code org/servlet/bla.jsp}</li>
 * <li>{@code com/{filename:\\w+}.jsp} will match {@code com/test.jsp} and assign the value {@code test}
 * to the {@code filename} variable</li>
 * </ul>
 *
 * <p><strong>Note:</strong> a pattern and a path must both be absolute or must
 * both be relative in order for the two to match. Therefore it is recommended
 * that users of this implementation to sanitize patterns in order to prefix
 * them with "/" as it makes sense in the context in which they're used.
 * /

符号的规则定义标准

• ? 匹配1个字符
• • 匹配0个或多个字符
• ** 匹配路径中的0个或多个目录
• {spring:[a-z]+} 将正则表达式[a-z]+匹配到的值，赋值给名为spring的路径变量。
  必须是完全匹配才行，在SpringMVC中只有完全匹配才会进入controller层的方法

符号 ?

和其它几个不一样的是? 要求必须为一个字符，并且不能是代表路径分隔符的/。

@RequestMapping("/index?")
@ResponseBody
public String index(){
    return "index.html";
 }

结果

index           false 404错误(必须要有一个字符)
index/          false 404错误(不能为"/")
indexab         false 404错误(不能是多个字符)
indexa          true  输出页面index.html

符号 *

• ，虽然可以匹配多个任意的字符，但是，无法用 * 可以替代 ** ，因为 * 代表的多个任意字符组成的字符串不能是个目录或者说路径.也就是说，* 并不能拿来替代 **.

示例代码:

@RequestMapping("/index*")
@ResponseBody
public String index(){
    return "index.html";
}

结果:

index           true  输出index.html(可以为0字符)
index/          true  输出 index.html(可以为"/")
indexa          true  输出 index.html(可以为1个字符)
indexabc        true  输出 index.html(可以为多个字符)
index/a         false 404错误("/a"是一个路径)

符号 **

0个或多个目录.** 代表的字符串本身不一定要包含 /

@RequestMapping("/index/**/a")
@ResponseBody
public String index(){
    return "index.html";
}

结果:

index/a         true  输出 index.html(可以为0个目录)
index/x/a       true  输出 index.html(可以为一个目录)
index/x/z/c/a   true  输出 index.html(可以为多个目录)

符号 {spring:[a-z]+}

其它的关于 AntPathMatcher 的文章里,对 {spring:[a-z]+} 的匹配大多是只字未提.这里补充下.

示例代码:

@RequestMapping("/index/{username:[a-b]+}")
@ResponseBody
public String index(@PathVariable("username") String username){
System.out.println(username);
return username;
}

结果:

index/ab true 输出 ab
index/abbaaa true 输出 abbaaa
index/a false 404错误
index/ac false 404错误

需求：我在做rbac权限校验的时候，设置管理员的访问路径为/admin/**,希望所有的开头为/admin/的uri操作地址都能进行匹配判断。

手动使用方式

• AntPathMatcher不仅可以匹配Spring的@RequestMapping路径，也可以用来匹配各种字符串，包括文件路径等。
• AntPathMatcher默认路径分隔符为“/”，而在匹配文件路径时，需要注意Windows下路径分隔符为“\”，Linux下为“/”，写法即为：

初始化创建操作

匹配文件路径，使用AntPathMatcher创建一个对象时，需要注意AntPathMatcher也有有参构造，传递路径分隔符参数pathSeparator，对于文件路径的匹配来说，则需要根据不同的操作系统来传递各自的文件分隔符，以此防止匹配文件路径错误。

AntPathMatcher matcher = new AntPathMatcher(File.separator)；
AntPathMatcher matcher = new AntPathMatcher(System.getProperty("file.separator"))；

执行匹配操作

import org.springframework.util.AntPathMatcher;
String content = "/admin/acuff";
String pattern = "/admin/**";
System.out.println(antPathMatcher.match(pattern, content));

最长匹配原则(has more characters)

最长匹配规则（has more characters），即越精确的模式越会被优先匹配到。例如，URL请求/app/dir/file.jsp，现在存在两个路径匹配模式/**/.jsp和/app/dir/.jsp，那么会根据模式/app/dir/*.jsp来匹配。

当然如果觉得这个工具还不够强大，还可以使用RegexRequestMatcher ，它支持使用正则表达式对URL地址进行匹配。如果你觉得这些都不够强大可以自己重写 RequestMatcher接口来进行定制的路由匹配规则

摘取网上的案例参考Sample

    // test exact matching
    assertTrue(pathMatcher.match("test", "test"));
    assertTrue(pathMatcher.match("/test", "/test"));
    assertTrue(pathMatcher.match("http://example.org", "http://example.org")); // SPR-14141
    assertFalse(pathMatcher.match("/test.jpg", "test.jpg"));
    assertFalse(pathMatcher.match("test", "/test"));
    assertFalse(pathMatcher.match("/test", "test"));
 
    // test matching with ?'s
    assertTrue(pathMatcher.match("t?st", "test"));
    assertTrue(pathMatcher.match("??st", "test"));
    assertTrue(pathMatcher.match("tes?", "test"));
    assertTrue(pathMatcher.match("te??", "test"));
    assertTrue(pathMatcher.match("?es?", "test"));
    assertFalse(pathMatcher.match("tes?", "tes"));
    assertFalse(pathMatcher.match("tes?", "testt"));
    assertFalse(pathMatcher.match("tes?", "tsst"));
 
    // test matching with *'s
    assertTrue(pathMatcher.match("*", "test"));
    assertTrue(pathMatcher.match("test*", "test"));
    assertTrue(pathMatcher.match("test*", "testTest"));
    assertTrue(pathMatcher.match("test/*", "test/Test"));
    assertTrue(pathMatcher.match("test/*", "test/t"));
    assertTrue(pathMatcher.match("test/*", "test/"));
    assertTrue(pathMatcher.match("*test*", "AnothertestTest"));
    assertTrue(pathMatcher.match("*test", "Anothertest"));
    assertTrue(pathMatcher.match("*.*", "test."));
    assertTrue(pathMatcher.match("*.*", "test.test"));
    assertTrue(pathMatcher.match("*.*", "test.test.test"));
    assertTrue(pathMatcher.match("test*aaa", "testblaaaa"));
    assertFalse(pathMatcher.match("test*", "tst"));
    assertFalse(pathMatcher.match("test*", "tsttest"));
    assertFalse(pathMatcher.match("test*", "test/"));
    assertFalse(pathMatcher.match("test*", "test/t"));
    assertFalse(pathMatcher.match("test/*", "test"));
    assertFalse(pathMatcher.match("*test*", "tsttst"));
    assertFalse(pathMatcher.match("*test", "tsttst"));
    assertFalse(pathMatcher.match("*.*", "tsttst"));
    assertFalse(pathMatcher.match("test*aaa", "test"));
    assertFalse(pathMatcher.match("test*aaa", "testblaaab"));
 
    // test matching with ?'s and /'s
    assertTrue(pathMatcher.match("/?", "/a"));
    assertTrue(pathMatcher.match("/?/a", "/a/a"));
    assertTrue(pathMatcher.match("/a/?", "/a/b"));
    assertTrue(pathMatcher.match("/??/a", "/aa/a"));
    assertTrue(pathMatcher.match("/a/??", "/a/bb"));
    assertTrue(pathMatcher.match("/?", "/a"));
 
    // test matching with **'s
    assertTrue(pathMatcher.match("/**", "/testing/testing"));
    assertTrue(pathMatcher.match("/*/**", "/testing/testing"));
    assertTrue(pathMatcher.match("/**/*", "/testing/testing"));
    assertTrue(pathMatcher.match("/bla/**/bla", "/bla/testing/testing/bla"));
    assertTrue(pathMatcher.match("/bla/**/bla", "/bla/testing/testing/bla/bla"));
    assertTrue(pathMatcher.match("/**/test", "/bla/bla/test"));
    assertTrue(pathMatcher.match("/bla/**/**/bla", "/bla/bla/bla/bla/bla/bla"));
    assertTrue(pathMatcher.match("/bla*bla/test", "/blaXXXbla/test"));
    assertTrue(pathMatcher.match("/*bla/test", "/XXXbla/test"));
    assertFalse(pathMatcher.match("/bla*bla/test", "/blaXXXbl/test"));
    assertFalse(pathMatcher.match("/*bla/test", "XXXblab/test"));
    assertFalse(pathMatcher.match("/*bla/test", "XXXbl/test"));
 
    assertFalse(pathMatcher.match("/????", "/bala/bla"));
    assertFalse(pathMatcher.match("/**/*bla", "/bla/bla/bla/bbb"));
 
    assertTrue(pathMatcher.match("/*bla*/**/bla/**", "/XXXblaXXXX/testing/testing/bla/testing/testing/"));
    assertTrue(pathMatcher.match("/*bla*/**/bla/*", "/XXXblaXXXX/testing/testing/bla/testing"));
    assertTrue(pathMatcher.match("/*bla*/**/bla/**", "/XXXblaXXXX/testing/testing/bla/testing/testing"));
    assertTrue(pathMatcher.match("/*bla*/**/bla/**", "/XXXblaXXXX/testing/testing/bla/testing/testing.jpg"));
 
    assertTrue(pathMatcher.match("*bla*/**/bla/**", "XXXblaXXXX/testing/testing/bla/testing/testing/"));
    assertTrue(pathMatcher.match("*bla*/**/bla/*", "XXXblaXXXX/testing/testing/bla/testing"));
    assertTrue(pathMatcher.match("*bla*/**/bla/**", "XXXblaXXXX/testing/testing/bla/testing/testing"));
    assertFalse(pathMatcher.match("*bla*/**/bla/*", "XXXblaXXXX/testing/testing/bla/testing/testing"));
 
    assertFalse(pathMatcher.match("/x/x/**/bla", "/x/x/x/"));
 
    assertTrue(pathMatcher.match("/foo/bar/**", "/foo/bar")) ;
 
    assertTrue(pathMatcher.match("", ""));
 
    assertTrue(pathMatcher.match("/{bla}.*", "/testing.html"));

spring mvc url地址匹配工具类

AntPathRequestMatcher

在spring mvc 中我们会经常使用//.jsp、/app//dir/file.、/**/example 、/app/.x 类似于这样语法而负责真正判断是否匹配的工具类就是AntPathRequestMatcher