SpringMVC的路径匹配规则是依照Ant的来的.

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(来自Spring AntPathMatcher源码注释):

 * {@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/**/test.jsp</code> &mdash; matches all {@code test.jsp}
 * files underneath the {@code com} path</li>
 * <li><code>org/springframework/**/*.jsp</code> &mdash; matches all
 * {@code .jsp} files underneath the {@code org/springframework} path</li>
 * <li><code>org/**/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.

换成人话就是:

• ? 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.(PS: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)

一个一个的分析.

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(){
    System.out.println("11");
    return "11";
}

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 11

符号 *

*,虽然可以匹配多个任意的字符,但是,如果你以为 * 可以替代 ** 那就错了,* 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(){
    System.out.println("11");
    return "11";
}

结果:

index           true  输出 11(可以为0字符)
index/          true  输出 11(可以为"/")
indexa          true  输出 11(可以为1个字符)
indexabc        true  输出 11(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(){
    System.out.println();
    return "11";
}

结果:

index/a         true  输出 11(可以为0个目录)
index/x/a       true  输出 11(可以为一个目录)
index/x/z/c/a   true  输出 11(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

附录(完整测试用例)

节选自 AntPathMatcherTests.不得不说 Spring 的测试用例写的实在是太完善了.

// 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"));