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The Spring Batch Infrastructure is a set of low-level components, interfaces and tools for batch processing applications and optimisations.
/*
* Copyright 2006-2007 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.batch.item;
import java.io.Serializable;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import java.util.Map.Entry;
import org.springframework.util.Assert;
/**
* Object representing a context for an {@link ItemStream}. It is a thin
* wrapper for a map that allows optionally for type safety on reads. It also
* allows for dirty checking by setting a 'dirty' flag whenever any put is
* called.
*
* @author Lucas Ward
* @author Douglas Kaminsky
*/
public class ExecutionContext {
private boolean dirty = false;
private final Map map;
/**
* Default constructor. Initializes a new execution context with an
* empty internal map.
*/
public ExecutionContext() {
map = new HashMap();
}
/**
* Initializes a new execution context with the contents of another map.
*
* @param map Initial contents of context.
*/
public ExecutionContext(Map map) {
this.map = map;
}
/**
* Adds a String value to the context.
*
* @param key Key to add to context
* @param value Value to associate with key
*/
public void putString(String key, String value) {
put(key, value);
}
/**
* Adds a Long value to the context.
*
* @param key Key to add to context
* @param value Value to associate with key
*/
public void putLong(String key, long value) {
put(key, new Long(value));
}
/**
* Add a Double value to the context.
*
* @param key Key to add to context
* @param value Value to associate with key
*/
public void putDouble(String key, double value) {
put(key, new Double(value));
}
/**
* Add an Object value to the context (must be Serializable).
*
* @param key Key to add to context
* @param value Value to associate with key
*/
public void put(String key, Object value) {
if(value != null){
Assert.isInstanceOf(Serializable.class, value, "Value: [ " + value + "must be serializable.");
}
dirty = true;
map.put(key, value);
}
/**
* Indicates if context has been changed with a "put" operation since the
* dirty flag was last cleared. Note that the last time the flag was cleared
* might correspond to creation of the context.
*
* @return True if "put" operation has occurred since flag was last cleared
*/
public boolean isDirty() {
return dirty;
}
/**
* Typesafe Getter for the String represented by the provided key.
*
* @param key The key to get a value for
* @return The String value
*/
public String getString(String key) {
return (String) readAndValidate(key, String.class);
}
/**
* Typesafe Getter for the Long represented by the provided key.
*
* @param key The key to get a value for
* @return The Long value
*/
public long getLong(String key) {
return ((Long) readAndValidate(key, Long.class)).longValue();
}
/**
* Typesafe Getter for the Double represented by the provided key.
*
* @param key The key to get a value for
* @return The Double value
*/
public double getDouble(String key) {
return ((Double) readAndValidate(key, Double.class)).doubleValue();
}
/**
* Getter for the value represented by the provided key.
*
* @param key The key to get a value for
* @return The value represented by the given key
*/
public Object get(String key) {
return map.get(key);
}
/**
* Utility method that attempts to take a value represented by a given
* key and validate it as a member of the specified type.
*
* @param key The key to validate a value for
* @param type Class against which value should be validated
* @return Value typed to the specified Class
*/
private Object readAndValidate(String key, Class type) {
Object value = map.get(key);
if (!type.isInstance(value)) {
throw new ClassCastException("Value for key=[" + key + "] is not of type: [" + type + "], it is ["
+ (value == null ? null : "(" + value.getClass() + ")" + value) + "]");
}
return value;
}
/**
* Indicates whether or not the context is empty.
*
* @return True if the context has no entries, false otherwise.
* @see java.util.Map#isEmpty()
*/
public boolean isEmpty() {
return map.isEmpty();
}
/**
* Clears the dirty flag.
*/
public void clearDirtyFlag() {
dirty = false;
}
/**
* Returns the entry set containing the contents of this context.
*
* @return A set representing the contents of the context
* @see java.util.Map#entrySet()
*/
public Set entrySet() {
return map.entrySet();
}
/**
* Indicates whether or not a key is represented in this context.
*
* @param key Key to check existence for
* @return True if key is represented in context, false otherwise
* @see java.util.Map#containsKey(Object)
*/
public boolean containsKey(String key) {
return map.containsKey(key);
}
/**
* Indicates whether or not a value is represented in this context.
*
* @param value Value to check existence for
* @return True if value is represented in context, false otherwise
* @see java.util.Map#containsValue(Object)
*/
public boolean containsValue(Object value) {
return map.containsValue(value);
}
/**
* Returns a Properties object containing String
* versions of the contents of the context.
*
* @return Contents of context as a {@link java.util.Properties}
*/
public Properties getProperties() {
Properties props = new Properties();
for (Iterator it = map.entrySet().iterator(); it.hasNext();) {
Entry entry = (Entry) it.next();
props.setProperty(entry.getKey().toString(), entry.getValue().toString());
}
return props;
}
/*
* (non-Javadoc)
* @see java.lang.Object#equals(java.lang.Object)
*/
public boolean equals(Object obj) {
if (obj instanceof ExecutionContext == false) {
return false;
}
if (this == obj) {
return true;
}
ExecutionContext rhs = (ExecutionContext) obj;
return this.entrySet().equals(rhs.entrySet());
}
/*
* (non-Javadoc)
* @see java.lang.Object#hashCode()
*/
public int hashCode() {
return map.hashCode();
}
/*
* (non-Javadoc)
* @see java.lang.Object#toString()
*/
public String toString() {
return map.toString();
}
/**
* Returns number of entries in the context
*
* @return Number of entries in the context
* @see java.util.Map#size()
*/
public int size() {
return map.size();
}
}