Question

我正在从数据库中读取属性文件。我检查了java.util.Properties，并且没有方法可以从String实例进行解析。有没有办法做到这一点？

Answer 1

你是对的java.util.Properties没有方法可以从String读取 - 但实际上它有更通用的方法可以从InputStream或{{1 }}

因此，如果您有某种方式将Reader作为其中任何一种呈现，即可以逐个有效地迭代字符的来源，则可以调用load。这感觉它应该存在，事实确实如此 - java.io.StringReader。

然后，把它放在一起非常简单：

String

Answer 2

我使用此代码从单个DB列加载属性

public Properties buildProperties(String propertiesFromString, String entrySeparator) throws IOException {
    Properties properties = new Properties();
    properties.load(new StringReader(propertiesFromString.replaceAll(entrySeparator, "\n")));
    return properties;
}

通过简单的测试

@Test
public void testProperties() throws Exception {
    Properties properties = buildProperties("A=1;B=2;Z=x",";");
    assertEquals("1", properties.getProperty("A"));        
    assertEquals("2", properties.getProperty("B"));        
    assertEquals("3", properties.getProperty("C","3"));        
    assertNull(properties.getProperty("Y"));
    assertEquals("x", properties.getProperty("Z"));  
}

Answer 3

我们遇到了类似的问题，上述内容对我们无效。

然而，下面的确如此。

def content = readFile 'gradle.properties'

Properties properties = new Properties()
InputStream is = new ByteArrayInputStream(content.getBytes());
properties.load(is)

def runtimeString = 'SERVICE_VERSION_MINOR'
echo properties."$runtimeString"
SERVICE_VERSION_MINOR = properties."$runtimeString"
echo SERVICE_VERSION_MINOR

Answer 4

这两个实用程序方法可以通过java.util.Properties对象向String写入和读取：

/**
 * Converts a {@link Properties} object to {@link String} and you can
 * also provide a description for the output.
 *
 * @param props an input {@link Properties} to be converted to {@link String}
 * @param desc  an input description for the output
 * @return an output String that could easily parse back to {@link Properties} object
 * @throws IOException If writing encounter a problem or if an I/O error occurs.
 */
private static String convert2String(final Properties props, String desc) throws IOException {
    final StringWriter sw = new StringWriter();
    String propStr;
    try {
        props.store(sw, desc);
        propStr = sw.toString();
    } finally {
        if (sw != null) {
            sw.close();
        }
    }

    return propStr;
}


/**
 * Converts {@link String} to {@link Properties}
 * @param propsStr an {@link String} input that is saved via convert2String method
 * @return a {@link Properties} object
 * @throws IOException if an error occurred when reading from the {@link StringReader}
 */
private static Properties convert2Properties(final String propsStr) throws IOException {
    final Properties props = new Properties();
    final StringReader sr = new StringReader(propsStr);
    try {
        props.load(sr);
    } finally {
        if (sr != null)
            sr.close();
    }

    return props;
}

我发现以上两种方法在有很多属性时很有用并且您想将所有这些都保存在storage or database中，并且您不想创建一个庞大的key-value存储表。

将字符串解析为属性

4 个答案: