View PDF Files in salesforce.com

Controller:

public without sharing class InlinePdfController {

    public Boolean attachmentExists {

        get;

        set;

    }

    public Boolean contentPdf {

        get;

        set;

    }

    public Id attachmentId {

        get;

        set;

    }

    public InlinePDFController(ApexPages.StandardController standardController) {

        Id accountId = '0019000000YSebM';

        List < Attachment > attachments = [SELECT Id, Name, ContentType, ParentId

            FROM Attachment

            WHERE ParentId = : accountId

            AND Name like '%report_a0W3000000lMuNgEAK.pdf%'

            ORDER BY LastModifiedDate DESC

        ];

        attachmentExists = false;

        contentPdf = false;

        if (attachments.size() > 0) {

            attachmentExists = true;

            Attachment a = attachments[0];

            if (a.ContentType != null && ((a.ContentType.toLowerCase().indexOf('pdf') > -1) || (a.Name.toLowerCase().endsWith('.pdf')))) {

                contentPdf = true;

            }

            attachmentId = a.Id;

        }

    }

}

visual force Page:

<apex:page standardController="Account" extensions="InlinePdfController" showHeader="false" sidebar="false">

    <apex:outputPanel layout="none" rendered="{!AND(attachmentExists,contentPdf)}">

        <script type="text/javascript">

            document.location.href = '/servlet/servlet.FileDownload?file={!attachmentId}';

        </script>

    </apex:outputPanel>

    <apex:outputPanel layout="block" rendered="{!AND(attachmentExists,NOT(contentPdf))}">

        Attachment is not in PDF format. 

    </apex:outputPanel>

    <apex:outputPanel rendered="{!NOT(attachmentExists)}">

        No attachment found.

    </apex:outputPanel>

</apex:page>