Adds an attachment builder that supports InputStream content.

src/main/java/com/sendgrid/helpers/mail/objects/Attachments.java

@@ -1,8 +1,12 @@
 package com.sendgrid;
 
+import com.fasterxml.jackson.annotation.JsonIgnoreType;
 import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonInclude.Include;
 import com.fasterxml.jackson.annotation.JsonProperty;
+import org.apache.commons.codec.binary.Base64;
+
+import java.io.*;
 
 @JsonInclude(Include.NON_DEFAULT)
 public class Attachments {
@@ -56,4 +60,81 @@ public String getContentId() {
   public void setContentId(String contentId) {
     this.contentId = contentId;
   }
+
+  @JsonIgnoreType
+  public static class Builder {
+
+    private static final int BYTE_BUFFER_SIZE = 4096;
+
+    private String fileName;
+    private String content;
+    private String type;
+    private String disposition;
+    private String contentId;
+
+    public Builder(String fileName, InputStream content) {
+      if (fileName == null) {
+        throw new IllegalArgumentException("File name mustn't be null");
+      }
+
+      if (content == null) {
+        throw new IllegalArgumentException("Content mustn't be null");
+      }
+
+      this.fileName = fileName;
+      this.content = encodeToBase64(content);
+    }
+
+    public Builder(String fileName, String content) {
+      if (fileName == null) {
+        throw new IllegalArgumentException("File name mustn't be null");
+      }
+
+      if (content == null) {
+        throw new IllegalArgumentException("Content mustn't be null");
+      }
+
+      this.fileName = fileName;
+      this.content = content;
+    }
+
+    private String encodeToBase64(InputStream content) {
+      int read = 0;
+      byte[] bytes = new byte[BYTE_BUFFER_SIZE];
+      try(ByteArrayOutputStream baos = new ByteArrayOutputStream()) {
+        while ((read = content.read(bytes)) != -1) {
+          baos.write(bytes, 0, read);
+        }
+
+        return Base64.encodeBase64String(baos.toByteArray());
+      } catch (IOException e) {
+        throw new RuntimeException("Unable to convert content stream to base 64 encoded string", e);
+      }
+    }
+
+    public Builder withType(String type) {
+      this.type = type;
+      return this;
+    }
+
+    public Builder withDisposition(String disposition) {
+      this.disposition = disposition;
+      return this;
+    }
+
+    public Builder withContentId(String contentId) {
+      this.contentId = contentId;
+      return this;
+    }
+
+    public Attachments build() {
+      Attachments attachments = new Attachments();
+      attachments.setContent(content);
+      attachments.setFilename(fileName);
+      attachments.setDisposition(disposition);
+      attachments.setContentId(contentId);
+      attachments.setType(type);
+      return attachments;
+    }
+  }
 }

src/test/java/com/sendgrid/helpers/AttachmentBuilderTest.java

@@ -0,0 +1,49 @@
+package com.sendgrid.helpers;
+
+import com.sendgrid.Attachments;
+import org.apache.commons.codec.binary.Base64;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.io.ByteArrayInputStream;
+import java.io.InputStream;
+import java.nio.charset.Charset;
+
+public class AttachmentBuilderTest {
+
+    @Test
+    public void testCreateAttachments() {
+        String fileName = "book.txt";
+        String type = "text/plain";
+        String content = "This test checks if the builder works fine";
+        InputStream contentStream = new ByteArrayInputStream(content.getBytes(Charset.forName("UTF-8")));
+        String contentId = "someId";
+        String dispositon = "someDisposition";
+
+        Attachments attachments = new Attachments.Builder(fileName, contentStream)
+                .withType(type)
+                .withContentId(contentId)
+                .withDisposition(dispositon)
+                .build();
+
+        Assert.assertEquals(attachments.getType(), type);
+        Assert.assertEquals(attachments.getFilename(), fileName);
+        Assert.assertEquals(attachments.getContentId(), contentId);
+        Assert.assertEquals(attachments.getDisposition(), dispositon);
+        Assert.assertEquals(attachments.getContent(), Base64.encodeBase64String(content.getBytes(Charset.forName("UTF-8"))));
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testCreateAttachmentsMissingRequiredFileNameParam() {
+        String content = "This test checks if the builder works fine";
+        InputStream contentStream = new ByteArrayInputStream(content.getBytes(Charset.forName("UTF-8")));
+        Attachments attachments = new Attachments.Builder(null, contentStream).build();
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testCreateAttachmentsMissingRequiredContentParam() {
+        String type = "text";
+        String content = null;
+        Attachments attachments = new Attachments.Builder(type, content).build();
+    }
+}