blocks|key|503900|text|基于您的异常，InputStream为空，这意味着类加载器找不到您的属性文件。我猜myProp.properties在你的项目的根目录中，如果是这样的话，你需要一个前面的斜杠：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|503901|InputStream+stream+=+loader.getResourceAsStream("/myProp.properties");|code-block|syntax|javascript|503902|entityMap^0|7|B|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

Based on your exception, the <code>InputStream</code> is null, this means the class loader is not finding your properties file. I'm guessing that myProp.properties is in the root of your project, if that's the case, you need a preceding slash:

<pre><code>InputStream stream = loader.getResourceAsStream("/myProp.properties");
</code></pre>

blocks|key|720190|text|您可以在此页面上找到相关信息：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|720191|http://www.mkyong.com/java/java-properties-file-examples/|offset|length|720192|Properties+prop+=+new+Properties();
try+{
++++//load+a+properties+file+from+class+path,+inside+static+method
++++prop.load(App.class.getClassLoader().getResourceAsStream("config.properties"));

++++//get+the+property+value+and+print+it+out
++++System.out.println(prop.getProperty("database"));
++++System.out.println(prop.getProperty("dbuser"));
++++System.out.println(prop.getProperty("dbpassword"));

}+
catch+(IOException+ex)+{
++++ex.printStackTrace();
}|code-block|syntax|javascript|720193|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|1L|0|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|S|8|@]|9|@$D|T|E|U|1|V]]|A|$]]|$1|F|3|G|5|H|7|W|8|@]|9|@]|A|$I|J]]|$1|K|3|-4|5|6|7|X|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|C]]]]

You can find information on this page: 
<a href="http://www.mkyong.com/java/java-properties-file-examples/" rel="noreferrer">http://www.mkyong.com/java/java-properties-file-examples/</a>

<pre><code>Properties prop = new Properties();
try {
 //load a properties file from class path, inside static method
 prop.load(App.class.getClassLoader().getResourceAsStream("config.properties"));

 //get the property value and print it out
 System.out.println(prop.getProperty("database"));
 System.out.println(prop.getProperty("dbuser"));
 System.out.println(prop.getProperty("dbpassword"));

} 
catch (IOException ex) {
 ex.printStackTrace();
}
</code></pre>

blocks|key|504017|text|您可以使用ResourceBundle类来读取属性文件。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|504018|ResourceBundle+rb+=+ResourceBundle.getBundle("myProp.properties");|code-block|syntax|javascript|504019|entityMap^0|5|E|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

You can use <code>ResourceBundle</code> class to read the properties file.

<pre><code>ResourceBundle rb = ResourceBundle.getBundle("myProp.properties");
</code></pre>

blocks|key|720282|text|Properties+prop+=+new+Properties();

try+{
++++prop.load(new+FileInputStream("conf/filename.properties"));
}+catch+(IOException+e)+{
++++e.printStackTrace();
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|720283|基于项目根目录的conf/filename.properties|unstyled|offset|length|style|CODE|720284|entityMap^0|0|8|O|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|N|8|@$G|O|H|P|I|J]]|9|@]|A|$]]|$1|K|3|-4|5|F|7|Q|8|@]|9|@]|A|$]]]|L|$]]

<pre><code>Properties prop = new Properties();

try {
 prop.load(new FileInputStream("conf/filename.properties"));
} catch (IOException e) {
 e.printStackTrace();
}
</code></pre>

<code>conf/filename.properties</code> base on project root dir

blocks|key|720055|text|您的文件应该在类路径中以com/example/foo/myProps.properties的形式可用。然后将其加载为：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|720056|props.load(this.getClass().getResourceAsStream("myProps.properties"));|code-block|syntax|javascript|720057|entityMap^0|C|Y|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

Your file should be available as <code>com/example/foo/myProps.properties</code> in classpath. Then load it as:

<pre><code>props.load(this.getClass().getResourceAsStream("myProps.properties"));
</code></pre>

blocks|key|720670|text|如果您的资源不在src/+config.properties+/config.properties目录中，而是在项目的根目录中，那么您需要执行如下操作：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|720671|Properties+prop+=+new+Properties();++++++++++
File+configFile+=+new+File(myProp.properties);
InputStream+stream+=+new+FileInputStream(configFile);
prop.load(stream);|code-block|syntax|javascript|720672|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

if your config.properties is not in src/main/resource directory and it is in root directory of the project then you need to do somethinglike below :- 

<pre><code>Properties prop = new Properties(); 
File configFile = new File(myProp.properties);
InputStream stream = new FileInputStream(configFile);
prop.load(stream);
</code></pre>

blocks|key|503938|text|确保文件名正确，并且该文件实际位于类路径中。如果不是这种情况，则getResourceAsStream()将返回null，从而导致最后一行抛出异常。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|503939|如果myProp.properties位于项目的根目录中，请改用/myProp.properties。|503940|entityMap^0|W|L|0|W|I|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|P|8|@]|D|@]|E|$]]]|I|$]]

Make sure that the file name is correct and that the file is actually in the class path. <code>getResourceAsStream()</code> will return null if this is not the case which causes the last line to throw the exception.

If myProp.properties is in the root directory of your project, use <code>/myProp.properties</code> instead.

blocks|key|720230|text|您可以使用java.io.InputStream读取文件，如下图所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|720231|InputStream+inputStream+=+getClass().getClassLoader().getResourceAsStream(myProps.properties);+|code-block|syntax|javascript|720232|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You can use java.io.InputStream to read the file as shown below:

<pre><code>InputStream inputStream = getClass().getClassLoader().getResourceAsStream(myProps.properties); 
</code></pre>

blocks|key|720744|text|我看到这个问题是一个老问题。如果有人在未来偶然发现了这一点，我认为这是一种简单的方法。将属性文件保存在项目文件夹中。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|720745|++++++++FileReader+reader+=+new+FileReader("Config.properties");

++++++++Properties+prop+=+new+Properties();
++++++++prop.load(reader);|code-block|syntax|javascript|720746|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I see that the question is an old one. If anyone stumbles upon this in the future, I think this is one simple way of doing it. 
Keep the properties file in your project folder.

<pre><code> FileReader reader = new FileReader("Config.properties");

 Properties prop = new Properties();
 prop.load(reader);
</code></pre>

blocks|key|720474|text|这里的许多答案描述了一些危险的方法，它们实例化文件输入流，但没有获得对输入流的引用，以便稍后关闭流。这会导致输入流悬空和内存泄漏。加载属性的正确方法应类似于以下内容：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|720475|++++Properties+prop+=+new+Properties();
++++try(InputStream+fis+=+new+FileInputStream("myProp.properties"))+{
++++++++prop.load(fis);
++++}
++++catch(Exception+e)+{
++++++++System.out.println("Unable+to+find+the+specified+properties+file");
++++++++e.printStackTrace();
++++++++return;
++++}|code-block|syntax|javascript|720476|注意try-with-resources块中文件输入流的实例化。由于FileInputStream是可自动关闭的，因此在退出try-with-resources块后，它将自动关闭。如果要使用简单的try块，则必须在finally块中使用fis.close();显式关闭它。|offset|length|style|CODE|720477|entityMap^0|0|0|2|I|Y|F|1Q|I|2Q|3|2Z|7|3A|C|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]|$I|T|J|U|K|L]|$I|V|J|W|K|L]|$I|X|J|Y|K|L]|$I|Z|J|10|K|L]|$I|11|J|12|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|13|8|@]|9|@]|A|$]]]|N|$]]

Many answers here describe dangerous methods where they instantiate a file input stream but do not get a reference to the input stream in order to close the stream later. This results in dangling input streams and memory leaks. The correct way of loading the properties should be similar to following:

<pre><code> Properties prop = new Properties();
 try(InputStream fis = new FileInputStream("myProp.properties")) {
 prop.load(fis);
 }
 catch(Exception e) {
 System.out.println("Unable to find the specified properties file");
 e.printStackTrace();
 return;
 }
</code></pre>

Note the instantiating of the file input stream in <code>try-with-resources</code> block. Since a <code>FileInputStream</code> is autocloseable, it will be automatically closed after the <code>try-with-resources</code> block is exited. If you want to use a simple <code>try</code> block, you must explicitly close it using <code>fis.close();</code> in the <code>finally</code> block.

blocks|key|504407|text|当前的答案都没有显示InputStream正在关闭(这将泄漏文件描述符)，并且/或者在找不到资源时不处理.getResourceAsStream()返回null+(这将导致NullPointerException带有令人困惑的消息"inStream+parameter+is+null")。您需要的内容如下所示：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|504408|String+propertiesFilename+=+"server.properties";
Properties+prop+=+new+Properties();
try+(var+inputStream+=+getClass().getClassLoader().getResourceAsStream(propertiesFilename))+{
++++if+(inputStream+==+null)+{
++++++++throw+new+FileNotFoundException(propertiesFilename);
++++}
++++prop.load(inputStream);
}+catch+(IOException+e)+{
++++throw+new+RuntimeException(
++++++++++++++++"Could+not+read+"+%2B+propertiesFilename+%2B+"+resource+file:+"+%2B+e);
}|code-block|syntax|javascript|504409|entityMap^0|A|B|1G|M|2E|K|37|S|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]|$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|L|$]]

None of the current answers show the <code>InputStream</code> being closed (this will leak a file descriptor), and/or don't deal with <code>.getResourceAsStream()</code> returning null when the resource is not found (this will lead to a <code>NullPointerException</code> with the confusing message, <code>"inStream parameter is null"</code>). You need something like the following:

<pre><code>String propertiesFilename = "server.properties";
Properties prop = new Properties();
try (var inputStream = getClass().getClassLoader().getResourceAsStream(propertiesFilename)) {
 if (inputStream == null) {
 throw new FileNotFoundException(propertiesFilename);
 }
 prop.load(inputStream);
} catch (IOException e) {
 throw new RuntimeException(
 "Could not read " + propertiesFilename + " resource file: " + e);
}
</code></pre>

blocks|key|720368|text|对于以原始顺序读取属性文件：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|720369|++++File+file+=+new+File("../config/edc.properties");
++++PropertiesConfiguration+config+=+new+PropertiesConfiguration();
++++PropertiesConfigurationLayout+layout+=+new+PropertiesConfigurationLayout(config);
++++layout.load(new+InputStreamReader(new+FileInputStream(file)));

++++for(Object+propKey+:+layout.getKeys()){
++++++++PropertiesConfiguration+propval+=++layout.getConfiguration();
++++++++String+value+=+propval.getProperty((String)+propKey).toString();
++++++++out.print("Current+Key:"+%2B+propkey+%2B+"Current+Value:"+%2B+propval+%2B+" ");
++++}|code-block|syntax|javascript|720370|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

For Reading Properties file with its original order:

<pre><code> File file = new File("../config/edc.properties");
 PropertiesConfiguration config = new PropertiesConfiguration();
 PropertiesConfigurationLayout layout = new PropertiesConfigurationLayout(config);
 layout.load(new InputStreamReader(new FileInputStream(file)));

 for(Object propKey : layout.getKeys()){
 PropertiesConfiguration propval = layout.getConfiguration();
 String value = propval.getProperty((String) propKey).toString();
 out.print("Current Key:" + propkey + "Current Value:" + propval + "&lt;br&gt;");
 }
</code></pre>

blocks|key|504475|text|从src开始指定路径，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|504476|src/main/resources/myprop.proper|code-block|syntax|javascript|504477|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Specify the path starting from src as below:

<pre><code>src/main/resources/myprop.proper
</code></pre>

I have the following code trying to read a properties file:

<pre><code>Properties prop = new Properties();
ClassLoader loader = Thread.currentThread().getContextClassLoader(); 
InputStream stream = loader.getResourceAsStream("myProp.properties");
prop.load(stream);
</code></pre>

I get an exception at the last line. Specifically:

<pre><code>Exception in thread "main" java.lang.NullPointerException
at java.util.Properties$LineReader.readLine(Properties.java:418)
at java.util.Properties.load0(Properties.java:337)
at java.util.Properties.load(Properties.java:325)
at Assignment1.BaseStation.readPropertyFile(BaseStation.java:46)
at Assignment1.BaseStation.main(BaseStation.java:87)
</code></pre>

thanks,
Nikos

Reading Properties file in Java

我使用以下代码尝试读取属性文件：Properties prop = new Properties();ClassLoader loader = Thread.currentThread().getContextClassLoader();           InputStream stream = loader.getResourceAsStream("myProp.properties");p

问在Java中读取属性文件
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