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1   /*
2    * Copyright 2006-2007 the original author or authors.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package org.springframework.batch.support;
17  
18  import org.springframework.beans.factory.InitializingBean;
19  import org.springframework.util.Assert;
20  
21  /**
22   * Helper class that sets up a System property with a default value. A System
23   * property is created with the specified key name, and default value (i.e. if
24   * the property already exists it is not changed).
25   * 
26   * @author Dave Syer
27   * 
28   */
29  public class SystemPropertyInitializer implements InitializingBean {
30  
31  	/**
32  	 * Name of system property used by default.
33  	 */
34  	public static final String ENVIRONMENT = "org.springframework.batch.support.SystemPropertyInitializer.ENVIRONMENT";
35  
36  	private String keyName = ENVIRONMENT;
37  
38  	private String defaultValue;
39  
40  	/**
41  	 * Set the key name for the System property that is created. Defaults to
42  	 * {@link #ENVIRONMENT}.
43  	 * 
44  	 * @param keyName the key name to set
45  	 */
46  	public void setKeyName(String keyName) {
47  		this.keyName = keyName;
48  	}
49  
50  	/**
51  	 * Mandatory property specifying the default value of the System property.
52  	 * 
53  	 * @param defaultValue the default value to set
54  	 */
55  	public void setDefaultValue(String defaultValue) {
56  		this.defaultValue = defaultValue;
57  	}
58  
59  	/**
60  	 * Sets the System property with the provided name and default value.
61  	 * 
62  	 * @see InitializingBean#afterPropertiesSet()
63  	 */
64      @Override
65  	public void afterPropertiesSet() throws Exception {
66  		Assert.state(defaultValue != null || System.getProperty(keyName) != null,
67  				"Either a default value must be specified or the value should already be set for System property: "
68  						+ keyName);
69  		System.setProperty(keyName, System.getProperty(keyName, defaultValue));
70  	}
71  
72  }