Add support to use any type as a job parameter

This commit also changes the way job parameters
are parsed and persisted.

NB: This commit should ideally have been split
into two change sets. But the changes are tightly
related that is was not possible to separate them.

Related to:

* spring-projects#3960
* spring-projects#2122
* spring-projects#1035
* spring-projects#1983

Author: fmbenhassine

spring-batch-core/src/main/java/org/springframework/batch/core/DefaultJobKeyGenerator.java

@@ -44,14 +44,14 @@ public class DefaultJobKeyGenerator implements JobKeyGenerator<JobParameters> {
 	public String generateKey(JobParameters source) {
 
 		Assert.notNull(source, "source must not be null");
-		Map<String, JobParameter> props = source.getParameters();
+		Map<String, JobParameter<?>> props = source.getParameters();
 		StringBuilder stringBuffer = new StringBuilder();
 		List<String> keys = new ArrayList<>(props.keySet());
 		Collections.sort(keys);
 		for (String key : keys) {
-			JobParameter jobParameter = props.get(key);
+			JobParameter<?> jobParameter = props.get(key);
 			if (jobParameter.isIdentifying()) {
-				String value = jobParameter.getValue() == null ? "" : jobParameter.toString();
+				String value = jobParameter.toString();
 				stringBuffer.append(key).append("=").append(value).append(";");
 			}
 		}

spring-batch-core/src/main/java/org/springframework/batch/core/JobParameter.java

@@ -17,15 +17,14 @@
 package org.springframework.batch.core;
 
 import java.io.Serializable;
-import java.util.Date;
 
 import org.springframework.lang.NonNull;
 import org.springframework.util.Assert;
 
 /**
- * Domain representation of a parameter to a batch job. Only the following types can be
- * parameters: String, Long, Date, and Double. The identifying flag is used to indicate if
- * the parameter is to be used as part of the identification of a job instance.
+ * Domain representation of a parameter to a batch job. The identifying flag is used to
+ * indicate if the parameter is to be used as part of the identification of a job
+ * instance.
  *
  * @author Lucas Ward
  * @author Dave Syer
@@ -34,87 +33,35 @@
  * @since 2.0
  *
  */
-public class JobParameter implements Serializable {
+public class JobParameter<T> implements Serializable {
 
-	private final Object parameter;
+	private T value;
 
-	private final ParameterType parameterType;
+	private Class<T> type;
 
-	private final boolean identifying;
+	private boolean identifying;
 
 	/**
-	 * Construct a new {@code JobParameter} from a {@link String}.
-	 * @param parameter {@link String} instance. Must not be {@code null}.
-	 * @param identifying {@code true} if the {@code JobParameter} should be identifying.
+	 * reate a new {@link JobParameter}.
+	 * @param value the value of the parameter. Must not be {@code null}.
+	 * @param type the type of the parameter. Must not be {@code null}.
+	 * @param identifying true if the parameter is identifying. false otherwise.
 	 */
-	public JobParameter(@NonNull String parameter, boolean identifying) {
-		this(parameter, identifying, ParameterType.STRING);
-	}
-
-	/**
-	 * Construct a new {@code JobParameter} from a {@link Long}.
-	 * @param parameter {@link Long} instance. Must not be {@code null}.
-	 * @param identifying {@code true} if the {@code JobParameter} should be identifying.
-	 */
-	public JobParameter(@NonNull Long parameter, boolean identifying) {
-		this(parameter, identifying, ParameterType.LONG);
-	}
-
-	/**
-	 * Construct a new {@code JobParameter} from a {@link Date}.
-	 * @param parameter {@link Date} instance. Must not be {@code null}.
-	 * @param identifying {@code true} if the {@code JobParameter} should be identifying.
-	 */
-	public JobParameter(@NonNull Date parameter, boolean identifying) {
-		this(parameter, identifying, ParameterType.DATE);
-	}
-
-	/**
-	 * Construct a new {@code JobParameter} from a {@link Double}.
-	 * @param parameter {@link Double} instance. Must not be {@code null}.
-	 * @param identifying {@code true} if the {@code JobParameter} should be identifying.
-	 */
-	public JobParameter(@NonNull Double parameter, boolean identifying) {
-		this(parameter, identifying, ParameterType.DOUBLE);
-	}
-
-	private JobParameter(Object parameter, boolean identifying, ParameterType parameterType) {
-		Assert.notNull(parameter, "parameter must not be null");
-		this.parameter = parameter;
-		this.parameterType = parameterType;
+	public JobParameter(@NonNull T value, @NonNull Class<T> type, boolean identifying) {
+		Assert.notNull(value, "value must not be null");
+		Assert.notNull(value, "type must not be null");
+		this.value = value;
+		this.type = type;
 		this.identifying = identifying;
 	}
 
 	/**
-	 * Construct a new {@code JobParameter} from a {@link String}.
-	 * @param parameter A {@link String} instance.
+	 * Create a new identifying {@link JobParameter}.
+	 * @param value the value of the parameter. Must not be {@code null}.
+	 * @param type the type of the parameter. Must not be {@code null}.
 	 */
-	public JobParameter(String parameter) {
-		this(parameter, true);
-	}
-
-	/**
-	 * Construct a new {@code JobParameter} from a {@link Long}.
-	 * @param parameter A {@link Long} instance.
-	 */
-	public JobParameter(Long parameter) {
-		this(parameter, true);
-	}
-
-	/**
-	 * Construct a new {@code JobParameter} as a {@link Date}.
-	 * @param parameter A {@link Date} instance.
-	 */
-	public JobParameter(Date parameter) {
-		this(parameter, true);
-	}
-
-	/**
-	 * Construct a new {@code JobParameter} from a {@link Double}.
-	 * @param parameter A {@link Double} instance.
-	 */
-	public JobParameter(Double parameter) {
-		this(parameter, true);
+	public JobParameter(@NonNull T value, @NonNull Class<T> type) {
+		this(value, type, true);
 	}
 
 	/**
@@ -128,15 +75,16 @@ public boolean isIdentifying() {
 	/**
 	 * @return the value contained within this {@code JobParameter}.
 	 */
-	public Object getValue() {
-		return parameter;
+	public T getValue() {
+		return value;
 	}
 
 	/**
-	 * @return a {@link ParameterType} representing the type of this parameter.
+	 * Return the type of the parameter.
+	 * @return the type of the parameter
 	 */
-	public ParameterType getType() {
-		return parameterType;
+	public Class<T> getType() {
+		return type;
 	}
 
 	@Override
@@ -150,41 +98,17 @@ public boolean equals(Object obj) {
 		}
 
 		JobParameter rhs = (JobParameter) obj;
-		return parameterType == rhs.parameterType && parameter.equals(rhs.parameter);
+		return type == rhs.type && value.equals(rhs.value);
 	}
 
 	@Override
 	public String toString() {
-		return parameterType == ParameterType.DATE ? "" + ((Date) parameter).getTime() : parameter.toString();
+		return "{" + "value=" + value + ", type=" + type + ", identifying=" + identifying + '}';
 	}
 
 	@Override
 	public int hashCode() {
-		return 7 + 21 * parameter.hashCode();
-	}
-
-	/**
-	 * Enumeration representing the type of {@link JobParameter}.
-	 */
-	public enum ParameterType {
-
-		/**
-		 * String parameter type.
-		 */
-		STRING,
-		/**
-		 * Date parameter type.
-		 */
-		DATE,
-		/**
-		 * Long parameter type.
-		 */
-		LONG,
-		/**
-		 * Double parameter type.
-		 */
-		DOUBLE;
-
+		return 7 + 21 * value.hashCode();
 	}
 
 }

spring-batch-core/src/main/java/org/springframework/batch/core/JobParameters.java

@@ -17,14 +17,17 @@
 package org.springframework.batch.core;
 
 import java.io.Serializable;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Date;
 import java.util.LinkedHashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Properties;
 
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 /**
  * Value object representing runtime parameters to a batch job. Because the parameters
@@ -46,7 +49,7 @@
 @SuppressWarnings("serial")
 public class JobParameters implements Serializable {
 
-	private final Map<String, JobParameter> parameters;
+	private final Map<String, JobParameter<?>> parameters;
 
 	/**
 	 * Default constructor.
@@ -61,7 +64,7 @@ public JobParameters() {
 	 * @param parameters The {@link Map} that contains a {@code String} key and a
 	 * {@link JobParameter} value.
 	 */
-	public JobParameters(Map<String, JobParameter> parameters) {
+	public JobParameters(Map<String, JobParameter<?>> parameters) {
 		this.parameters = new LinkedHashMap<>(parameters);
 	}
 
@@ -75,8 +78,11 @@ public Long getLong(String key) {
 		if (!parameters.containsKey(key)) {
 			return null;
 		}
-		Object value = parameters.get(key).getValue();
-		return value == null ? null : ((Long) value).longValue();
+		JobParameter<?> jobParameter = parameters.get(key);
+		if (!jobParameter.getType().equals(Long.class)) {
+			throw new IllegalArgumentException("Key " + key + " is not of type Long");
+		}
+		return (Long) jobParameter.getValue();
 	}
 
 	/**
@@ -104,8 +110,14 @@ public Long getLong(String key, @Nullable Long defaultValue) {
 	 */
 	@Nullable
 	public String getString(String key) {
-		JobParameter value = parameters.get(key);
-		return value == null ? null : value.toString();
+		if (!parameters.containsKey(key)) {
+			return null;
+		}
+		JobParameter<?> jobParameter = parameters.get(key);
+		if (!jobParameter.getType().equals(String.class)) {
+			throw new IllegalArgumentException("Key " + key + " is not of type String");
+		}
+		return (String) jobParameter.getValue();
 	}
 
 	/**
@@ -136,8 +148,11 @@ public Double getDouble(String key) {
 		if (!parameters.containsKey(key)) {
 			return null;
 		}
-		Double value = (Double) parameters.get(key).getValue();
-		return value == null ? null : value.doubleValue();
+		JobParameter<?> jobParameter = parameters.get(key);
+		if (!jobParameter.getType().equals(Double.class)) {
+			throw new IllegalArgumentException("Key " + key + " is not of type Double");
+		}
+		return (Double) jobParameter.getValue();
 	}
 
 	/**
@@ -165,7 +180,14 @@ public Double getDouble(String key, @Nullable Double defaultValue) {
 	 */
 	@Nullable
 	public Date getDate(String key) {
-		return this.getDate(key, null);
+		if (!parameters.containsKey(key)) {
+			return null;
+		}
+		JobParameter<?> jobParameter = parameters.get(key);
+		if (!jobParameter.getType().equals(Date.class)) {
+			throw new IllegalArgumentException("Key " + key + " is not of type java.util.Date");
+		}
+		return (Date) jobParameter.getValue();
 	}
 
 	/**
@@ -179,19 +201,24 @@ public Date getDate(String key) {
 	@Nullable
 	public Date getDate(String key, @Nullable Date defaultValue) {
 		if (parameters.containsKey(key)) {
-			return (Date) parameters.get(key).getValue();
+			return getDate(key);
 		}
 		else {
 			return defaultValue;
 		}
 	}
 
+	@Nullable
+	public JobParameter<?> getParameter(String key) {
+		Assert.notNull(key, "key must not be null");
+		return parameters.get(key);
+	}
+
 	/**
-	 * Get a map of all parameters, including {@link String}, {@link Long}, and
-	 * {@link Date} types.
+	 * Get a map of all parameters.
 	 * @return an unmodifiable map containing all parameters.
 	 */
-	public Map<String, JobParameter> getParameters() {
+	public Map<String, JobParameter<?>> getParameters() {
 		return Collections.unmodifiableMap(parameters);
 	}
 
@@ -223,17 +250,25 @@ public int hashCode() {
 
 	@Override
 	public String toString() {
-		return parameters.toString();
+		List<String> parameters = new ArrayList<>();
+		for (Map.Entry<String, JobParameter<?>> entry : this.parameters.entrySet()) {
+			parameters.add(String.format("'%s':'%s'", entry.getKey(), entry.getValue()));
+		}
+		return new StringBuilder("{").append(String.join(",", parameters)).append("}").toString();
 	}
 
 	/**
 	 * @return The {@link Properties} that contain the key and values for the
 	 * {@link JobParameter} objects.
+	 * @deprecated since 5.0, scheduled for removal in 5.2. Use
+	 * {@link org.springframework.batch.core.converter.JobParametersConverter#getProperties(JobParameters)}
+	 *
 	 */
+	@Deprecated(since = "5.0", forRemoval = true)
 	public Properties toProperties() {
 		Properties props = new Properties();
 
-		for (Map.Entry<String, JobParameter> param : parameters.entrySet()) {
+		for (Map.Entry<String, JobParameter<?>> param : parameters.entrySet()) {
 			if (param.getValue() != null) {
 				props.put(param.getKey(), Objects.toString(param.getValue().toString(), ""));
 			}